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Bio-economic analysis of selected broiler breeder management practices

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Bio-economic analysis of selected broiler breeder management practices
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Fattori, Thomas Richard, 1950-
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English
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xiii, 172 leaves : ill. ; 29 cm.

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Dissertations, Academic -- Animal Science -- UF
Animal Science thesis Ph. D
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bibliography ( marcgt )
non-fiction ( marcgt )

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Thesis:
Thesis (Ph. D.)--University of Florida, 1989.
Bibliography:
Includes bibliographical references (leaves 160-170).
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Typescript.
General Note:
Vita.
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Electronic resources created as part of a prototype UF Institutional Repository and Faculty Papers project by the University of Florida.
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by Thomas Richard Fattori.

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University of Florida
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Copyright Thomas Richard Fattori. Permission granted to the University of Florida to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
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001561953 ( ALEPH )
22687645 ( OCLC )
AHH5653 ( NOTIS )

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BIO-ECONOMIC ANALYSIS OF SELECTED BROILER BREEDER MANAGEMENT PRACTICES

















BY


THOMAS RICHARD FATTORI


A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY


UNIVERSITY OF FLORIDA


1989

















ACKNOWLEDGMENTS


The author wishes to express his most sincere

appreciation to his co-advisors, Dr. Henry R. Wilson and Dr. Peter E. Hildebrand, for their guidance throughout the author's Doctor of Philosophy program. Their strong direction and support of the selected coursework and research program enabled an understanding of a broad range of issues important to poultry management.

Special appreciation is extended to other committee

members, Dr. Steve A. Ford, Dr. R. H. Harms, and Dr. F. Ben Mather, for their encouragement, technical advisement and guidance throughout the research program.

Additional gratitude is extended to the professors of the University of Florida Poultry Science Department, Mr. David P. Eberst, Mr. W. Gary Smith and the farm crew, and all members of the staff for their assistance in faciliting the work load over a long research period.

The author is also indebted to Mr. Harold Barnes and Gold Kist, Inc. for the cooperation and assistance in conducting research on-farm and whose advice was of great value.











Sincere appreciation is expressed to the author's

parents, Mr. and Mrs. L. A. Fattori, for their support and personal encouragement throughout the graduate program.

The author wishes to extend his deepest appreciation to his wife Maisha for her care and support of their home and family which freed the many hours needed to complete this program. Without her patient understanding this endeavor would have never been completed.


iii



















TABLE OF CONTENTS


Paae

ACKNOWLEDGMENTS. . ii

LIST OF TABLES. vi

LIST OF FIGURES . ix

ABSTRACT . Xii

CHAPTERS

I INTRODUCTION . . . 1

Problematic Situation . 3
Researchable Problems. 4
Hypotheess. . 5 Experimental Objectives . 6
Relevance to Farming Systems Research
and Extension . 9

II LITERATURE REVIEW. 10

Introduction . . 10 Weighing Programs. 11 Pullet Rearing Period . 20 Pullet-Layer Transition Period. 25
Breeder Hen Laying Period . 33

III TOWARDS AN APPROPRIATE STRATEGY
FOR WEIGHING BROILERS, BROILER BREEDER
PULLETS AND BREEDER HENS. 41

Introduction. 41 Materials and Methods . 43 Results and Discussion. 47

IV THE EFFECT OF SEVERE FEED RESTRICTION
DURING THE REARING PERIOD ON FEMALE
BROILER BREEDER REPRODUCTIVE PERFORMANCE. 66













Introduction . 66 Materials and Methods. 68
Results and Discussion.,. 72

V CHARACTERIZING THE ONSET OF SEXUAL MATURITY
IN FEED RESTRICTED BROILER BREEDER FEMALES. 92

Introduction. . . . 92 Materials and Methods. 94
Results and Discussion. 96

VI ECONOMIC ANALYSIS OF SEVERE FEED
RESTRICTION ON BROILER BREEDER PULLET
REARING AND BREEDER HATCHING EGG PRODUCTION. 117

Introduction .[. * 117 Materials and Methods. 120 Results and Discussion. 125

VII SUMMARY AND CONCLUSIONS., . 150

Weighing Programs . . 151 Feeding Programs.,. 153 Targeting Sexual Maturity .,. 155 Economic Analysis of Feeding Programs . 157

REFERENCES.*. . . 160

BIOGRAPHICAL SXETCH.***. 171

















LIST OF TABLES


Table Pafe

3-1 Effect of feeding time (ERL vs. LTE) and time
of day on non-laying broiler breeder female
mean body weight and weight change (Exp. 1). 56

3-2 Effect of scale type (ELC vs. SPR) and sample
units (IND vs. GRP), on mean adult breeder hen and breeder pullet body weight and uniformity
(SD), (Exp. 2) . 57

3-3 Effect of sample location (FDD vs. END) and
sample type (PND vs. FXD) on mean straight-run
broiler body weight and uniformity (SD),
(Exp. 3). . 58

3-4 Effect of sample location (FDD vs. END) at
various ages and by sample type (PND vs. FXD)
on mean pullet body weight and uniformity (SD),
(Exp. 3) . 59

3-5 Effect of sample location (FDD vs. END) at
various ages and by sample type (PND vs FXD) on
mean breeder hen body weight and uniformity (SD),
(Exp. 3) . . 60

3-6 Effect of sample location (FDD vs. END) on mean
breeder hen and pullet body weight gain (Exp. 3). 61

3-7 Classification of suspect outliers as true
outliers by testing mean body weight with an
outlier interval (� 3*SD) for broilers, pullets
and breeder hens (Exp. 3) . 62

3-8 Effect of sample size on mean and variance of
body weight for broilers, pullets and breeder
hens . . 63

4-1 Composition, calculated nutrient content and age
used for the starter and grower diets . 80

4-2 Daily nutrient intake of broiler breeders after
20 weeks of age. 81











4-3 Effect of feed treatment on growth, development
and mortality of breeder hens. 82

4-4 Effect of feed treatment on breeder hen mean
(� SEM) production performance. 83

4-5 Effect of feed treatment on hen-day production
for chronological and physiological ages . 84

4-6 Effect of feed treatment on mean (� SEM)
specific gravity (SG) and egg weight (EW), and
the correlation between these parameters at
various ages. 85

4-7 Effect of feed treatment on mean (� SEM)
hatchability of all eggs set (Hatch) and
fertility (Fert) at various ages. 86

4-8 Cumulative feed, crude protein and metabolizable
energy intake per bird at various chronological
and physiological ages and by feed treatment. 87

5-1 Correlation coefficient (r) and the significance
probability that the correlation is zero (P>/r/) for various physical attributes associated with
sexual maturity. 101

5-2 Effect of feed treatment (mean + SEM) on various
physical attributes associated with sexual
maturity . 103

5-3 Effect of feed treatment on bursa weight (mean +
SEM) and relative proportion of bursa and fat pad
to body weight. 105

5-4 Effect of feed treatment (mean + SEM) on various
physical attributes associated with sexual
maturity. 106

6-1 Base costs, production coefficients and + 20%
adjustments used in sensitivity analysis of a
pullet rearing enterprise. 135

6-2 Base costs, production coefficients and + 20%
adjustments used in sensitivity analysis of a
breeder hen laying enterprise. 136

6-3 Average total cost of a pullet survivor reared
to a common age by feeding program . 137


vii











6-4 Effect of feeding program on pullet rearing
average cost budget through 5% production,
calculated at base prices. 138

6-5 Effect of feeding program on breeder hen average
cost budget through 40 weeks of production, calculated at base prices and expressed as
dollars per survivor . 139

6-6 Effect of feeding program on breeder hen average
cost budget through 40 weeks of production, calculated at base prices and expressed as
dollars per dozen hatching eggs. 140

6-7 Average total cost of a dozen hatching eggs
produced to a common age by feeding program, calculated at base prices and before salvage
adjustments. . . 141

6-8 Live body weight (kg) by feeding program at
various transfer (laying house) ages and the
relative difference (%) among programs . 142


viii

















LIST OF FIGURES


Figure Page

3-1 Effect of early feeding schedule and time of
weighing on broiler breeder female body
weight (Exp. 1). 64

3-2 Cyclic changes in non-laying breeder female body
weight, on an early or late feeding schedule. 64

3-3 Frequency distribution of confidence intervals
for a fixed quantity of birds excluding outliers
(A) and all birds in a penned-up group (B). 65

4-1 Average weekly high (HI) and low (LO)
temperatures and hours of daylight (LIGHT)
during the research period. 88

4-2 Live body weight from hatching to 62 weeks of
age as affected by feed treatment. 88

4-3 Relationship between body weight (Y, g) and age
(X, d) as affected by feed treatment at 50%
production (flock maturity) . 89

4-4 Effect of feed treatment on hen-day
production (%). 90

4-5 Hen-day production of double-yolked eggs (%) as
affected by feed treatment. 91

4-6 Mean egg weight (g) and specific gravity (g/mL)
plotted over the production period for the STD
and -24% feed treatments. 91

5-1 Effect of feed treatment on shank length (mm)
with respect to age (wk) and body weight (g). 107

5-2 Effect of feed treatment on fat pad weight (g)
with respect to age (wk) and body weight (g). 108

5-3 Effect of feed treatment on pubic spread or arch
(cm) with respect to age (wk) and body
weight (g). . 109











5-4 Effect of feed treatment on head score (no.,
5=most developed) with respect to age (wk) and
body weight (g) . . 110

5-5 Effect of feed treatment on comb factor (cm-2)
with respect to age (wk) and body weight (g). 111

5-6 Effect of feed treatment on plasma total lipid
(mg/mL) with respect to age (wk) and
body weight (g) . . 112

5-7 Effect of feed treatment on oviduct weight (g)
with respect to age (wk) and body weight (g). 113

5-8 Effect of feed treatment on ovary weight (g)
with respect to age (wk) and body weight (g). 114

5-9 Relationship of mean bursa.weight (g) to body
weight (g) as affected by feed treatment
(TRT A=+8%, B=STD, C=-8%, D=-16%, and E=-24%). 115

5-10 Effect of feed treatment on shank length (mm)
with age (wk). 116

6-1 Average cost structure of a standard pullet
rearing program, at base prices. 143

6-2 Average cumulative feed cost for various
pullet feeding programs. 143

6-3 Sensitivity of pullet average total cost to
changes in component costs at 20, 25, and 30
weeks of age for the STD feeding program
(CHK=chick, PFD=pullet feed, PPAY=grower pay, PMRT=pullet mortality, DENSITY=pullet housing
density) . 144

6-4 Sensitivity of pullet average total cost to
changes in component costs at 20, 25, and 30
weeks of age for the -24% feeding program. 145

6-5 Effect of a 20% change in component costs on
average total cost per pullet survivor at 5%
production. 146

6-6 Average total cost of a dozen hatching eggs for
the STD and -24% feeding programs, with age. 146












6-7 Sensitivity of breeder hen average total cost
to changes in feed costs (BFD) or costs due to
breeder hen mortality (BMRT) at 40 weeks of production and for the STD or -24% feeding
programs . . . . . . 147

6-8 Sensitivity of breeder hen average total cost
to changes in pullet depreciation costs (PUL$) or
costs due to breeder hen mortality (BMRT) at 40
weeks of production for the STD and -24%
feeding programs . 148

6-9 Effect of changes in pullet housing density on
average total cost per pullet (ATC/P) at 5%
production. . 149

6-10 Effect of adjusted pullet housing density on
average total cost of a dozen hatching eggs
(ATC/E) on a STD and -24% feeding program, with
age . 149
















Abstract of Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy

BIO-ECONOMIC ANALYSIS OF SELECTED
BROILER BREEDER MANAGEMENT PRACTICES BY

THOMAS RICHARD FATTORI

December, 1989

Chairman: Henry R. Wilson
Cochairman: Peter E. Hildebrand Major Department: Animal Science (Poultry Science)


Studies were conducted to evaluate bird weighing procedures and the effect of selected broiler breeder management practices on pullet and breeder hen growth and reproductive performance.

Evaluations were made of the effects of sample and batch size, in-house locations, type of scale, time of weighing and procedure complexity used in the on-farm weighing of broiler breeder stock on body weight gain and uniformity. Time of weighing was shown to be an important source of error when estimating live weight gain. No significant differences in average body weight due to scale type or batch size could be detected. A significant location effect was found with breeder hens, but not with broilers or breeder pullets. It was determined that suspected outliers should not be rejected from the sample.


xii











The effect of quantitative feed restriction on breeder hen reproductive performance was determined. Proportional decreases in feed allocation below standard practices resulted in corresponding decreases in body weight, doubleyolked eggs and number of days in production to 64 weeks. Egg weight, fertility, hatchability, and female mortality to 64 wk of age were not significantly affected by feed treatment. A delay in sexual maturity caused a significant decrease in average hen-day production to 64 wk, but not in total settable eggs per hen-housed.

The effects of feed restriction on attributes

associated with sexual maturity (comb, bursa, fat pad, plasma lipid, ovary, oviduct, and shank), were characterized. The main effect was a delay in the development of these attributes without significantly altering their ultimate physiological values, with the exception of shank length which was permanently reduced by severe feed restriction.

The economic effect of severe feed restriction on

pullet rearing and breeder hen cost structures was analyzed. Average pullet rearing cost was increased by ca. 3% when feed restriction delayed maturity by 3 weeks. The resulting increased pullet depreciation cost was not offset in the laying period until ca. 67 wk of age. Projected average total costs beyond 67 wk were lower for severe restriction than standard feeding practices, especially if pullet housing density is adjusted to an equivalent bio-mass.


xiii

















CHAPTER I

INTRODUCTION


The Joint Council on Food and Agricultural Sciences has developed national research priorities in the area of animal production for a number of years. In 1988 the general area of reproductive efficiency was targeted as a fiscal priority for research, extension and higher education (Cook, 1988). Cook noted that this topic was particularly important to the broiler industry where growth rates and reproduction are negatively correlated. The Joint Council suggested that priority be given to research goals which develop technologies and educational programs that increase the efficiency and profitability of broiler breeder reproduction. The goals of this dissertation conform well with those identified by the Joint Council. Furthermore, this research endeavor has targeted the broiler breeder manager as its principal client and attempts to demonstrate how research findings can be applied to direct field use.

Perhaps the most significant change in the broiler meat industry over the last ten years was the transition from a production-driven to a market-driven industry. As American consumers increased their demand for value, convenience,













quality and nutrition from the food market place, broiler meat producers competed actively to fulfill these needs. Evidence of industry's ability to respond effectively to this dynamic consumer behavior is the fact that total per capita consumption of poultry meat increased consistently over this time period. Also, consumer demand drove further processed poultry products into all segments of the market place. Now, over 6,000 specialty products using chicken and other poultry are marketed by the poultry industry and further enhancement of this wide product line to meet the diverse wants of the consumer is expected to continue (Brown, 1989).

This change to a consumer orientation may seem distant from the main issue of this dissertation, but it has had a direct affect on broiler breeder reproductive efficiency and management practices. Primary breeder companies, those that market broiler breeder parent stock to the broiler industry, have shifted their selection emphasis to those phenotypic traits with the greatest bio-economic importance. For example, emphasis on selection for increased egg numbers and hatchability of parent stock lowers growth and feed efficiency performance in the broiler progeny. Conversely, emphasis on growth rate in the progeny will lower reproductive performance in the breeder house. The relative economic importance of parental reproductive traits such as egg production, hatchability, livability or breeder feed













conversion are not as great as such progeny traits as yield (with its associated characteristics, including grade and conformation), feed conversion and growth rate in todays market environment (Rishell, NA). A percentage change in processing yield will have a greater effect on profits than will an equal change in any of the other genetic traits considered in a breeding program.


Problematic Situation

Different breeding policies among the various primary breeders result in strains of birds that are suited for different market conditions. This genetic variability can be used to an advantage by broiler producers so that a flexible production response to consumer demand can be achieved. In fact it is not uncommon for a production complex to utilize several commercial breeds at the same time. The problematic situation being that each strain of bird is best managed by a specific set of procedures.

A successful broiler breeder management program is one that optimizes the use of feed, labor, capital and other resources in the production of placeable chicks per hen housed. The complexity of this challenge is made evident by the depth and diversity of possible factors that can impact either negatively or positively on the production process.

Management must account for and control variation in

the growth and development of a particular strain of broiler














breeder caused by differences in the physical and manageria. environments in which they are reared and bred. Those managers who approach breeder reproductive performance from a life cycle perspective will find that maintaining the proper balance between controlled growth and reproduction is an easier task than those who do not.


Researchable Problems
The primary objective of a broiler breeder management program is to carefully monitor and control each phase of growth and development during the life cycle, Breeder managers are required to constantly make decisions concerning feed formulation and allocation based on body weight information generated from a pullet weighing program or body weight and egg production information in the breeder hen program. Inaccurate information will result in inefficient and sometimes costly decisions--costly to the integrator (increased chick cost), hatching egg producer (lower payments) and society as a whole (higher meat cost) as resources are not used efficiently.

The researchable problems identified in this

dissertation relate to this decision making process on the part of the breeder manager. Specifically, the researchable problems arise from the breeder managers need to 1) establish an effective body weight monitoring and control program, 2) maximize the number of placeable chicks from a














breeder rearing and laying program, 3) target sexual maturity, and 4) optimize economic returns from pullet rearing and breeder hen laying programs.


Hypotheses
Hypothesis 1

If procedures for the on-farm weighing of broilers, broiler breeder pullets and breeder hens can be optimized with respect to the total time (cost) required to conduct the weighing program, then monetary returns to the growers, breeders and integrator will increase. Increased returns will result from more efficient use of labor and feed resources, as well as increased breeder reproductive performance.


Hypothesis 2

If the appropriate broiler breeder body weight growth curve resulting from a level of feed restriction can be identified, then reproductive performance (placeable chicks) of a housed flock can be maximized.


Hypothesis 3

If changes in the physical characteristics of a breeder hen that signal the onset of sexual maturity as she passes through the pullet-layer transition period can be identified for various degrees of severe feed restriction, then these













traits can be utilized to alert the breeder manager to ensuing increases in nutritional needs of the flock.


Hypothesis 4

If broiler breeders are severely feed restricted during the rearing period and the resulting biological response is an equivalent but delayed reproductive performance relative to standard practices then, economic returns to the pullet grower, hatching egg producer and broiler integrator from restricted feeding will be increased above levels derived from recommended practices.


Experimental Objectives


Rewarding Hypothesis 1

The experimental objectives regarding hypothesis 1 were to: 1. quantify the cyclic change in body weight over a 48 hour period;

2. illustrate the potential error in estimating weight gain when weighings are not conducted at the same time each weighing;

3. determine the effect of scale type, sample units, sample size, sample location, time of sampling and complexity of the procedures used in the on-farm weighing of broilers, broiler breeder pullets and breeder hens, on average body weight, body weight gain and uniformity;













and 4. determine the effect of subjectively removing suspected outliers from a sample group on average body weight estimates and uniformity.



Regarding Hypothesis 2

The experimental objectives regarding hypothesis 2 were to: 1. evaluate the broiler pullet growth response to various degrees of severe feed restriction;

2. evaluate the breeder hen growth and production response to various degrees of severe feed restriction;

3. evaluate changes in reproductive physiology related to severe feed restriction;

4. evaluate the effect of severe feed restriction on hatching egg characteristics; and 5. evaluate breeder hen technical efficiencies related to feed usage and production performance.



Regarding Hypothesis 3

The experimental objectives regarding hypothesis 3 were to: 1. quantify the effect of severe feed restriction on various physical attributes associated with sexual maturity through the pullet-layer transition period;

2. assess the degree of linear correlation among all quantified physical attributes at various ages;













3. characterize in graphic form the age and body weight relationships to changes in the various physical attributes;

and 4. relate findings from the characterization process to possible field applications.



Regarding Hypothesis 4

The experimental objectives regarding hypothesis 4 were to: 1. examine the effect of severe feed restriction on pullet rearing cost structure;

2. determine the cost of delayed sexual maturity due to various levels of severe feed restriction;

3. test the sensitivity of the average total cost of rearing a pullet to 5% production to changes in component costs;

4. examine the effect of severe feed restriction on breeder hen cost structure;

5. compare breeder hen average total costs on a survivor and per dozen hatching eggs basis;

6. test the sensitivity of average total cost of

breeder hen hatching egg production to changes in component costs;

7. estimate the changes in pullet rearing cost structure due to changes in pullet housing density; and 8. estimate the changes in breeder hen laying cost structure to changes in pullet housing density.













Relevance to Farmina Systems Research and Extension

The strength of the Farming Systems Research and Extension (FSR/E) approach to technology generation is derived, in part, from its systems perspective while accounting for the biological as well as the socio-economic factors that impact on the production process. The vertically integrated broiler production systems of today are highly complex by agricultural standards and economies of scale are required in their competitive marketplace. In such a system, savings of a hundredth of a cent per pound of product from increased technical efficiencies can translate into millions of dollars of added net income for growers, breeders and integrator.

Therefore, FSR/E methodology is perhaps the most

appropriate approach to technology generation at the breeder level in that it prescribes a complete socio-economic, as well as biological, analysis of the production system. The methodology utilized in this research drew upon multidisciplinary issues that ranged from information systems to the physiological aspects of sexual maturity. The result is a dissertation that is more comprehensive than would have been attained if "traditional" procedures were followed. Furthermore, client participation in problem identification and diagnoses was sought out, and diffusion of research findings back to the client was achieved in a workshop setting.

















CHAPTER II

LITERATURE REVIEW



Introduction

Information in the literature on various broiler

breeder management practices is relatively scarce. Even more surprising is the paucity of scientific research on such fundamental issues as weighing programs, bird and flock behavior, and economic analysis of production. This is unfortunate because managing today's broiler breeder is a complex practice that requires knowledge of the bird and the broad range of factors affecting it.

A review of the current literature reveals that two basic perspectives have been taken by researchers, one nutritional, the other physiological. The nutritional studies have focused on feeding programs and the nutritional requirements of the bird, whereas the physiological studies have focused on lighting programs and the physiological requirements for the initiation of sexual maturity. Both perspectives are interrelated and are better understood if examined under a common forum.

It is important to identify from the start a few of the principal causes of variation and conflicting findings in













the literature. Environmental effects such as photoperiod, temperature, humidity, and air and litter quality have a strong influence on maintenance, growth and production. Pullet management can interact with breeder management, especially when birds are moved into new housing for production. Differences in breeder strain, housing, equipment, feed ingredients, and feed and water quality can all be a source of variation in commercial performance as well as experimental discrepancy or error.

This review will examine the following areas of

interest: weighing programs and pullet rearing, pullet-layer transition, and breeder hen laying periods.



WeiQhina Programs

Weighing Methodoloqgy

A review of the current broiler breeder management

guides revealed a broad range of recommended sample weighing techniques. Recommendations ranged from no suggested methodology at all (Hubbard Farms, 1988-89, and Avian Farms International, 1989) to extensive procedures by Ross Poultry Breeders, Inc., (1986). The weighing techniques recommended by Ross include individually weighing every bird in a penned-up group (ca. 50 to 100 birds) every week from 4 wk of age through peak production.

Generally, most primary breeders recommend that birds

be individually weighed weekly, starting at 4 or 5 wk of age














and continued through peak production. All birds in a penned-up group should be weighed and the weighings should consistently occur on the off-feed day, at the same time (afternoon) and at the same locations in the house. Variation in the number of locations to use in a house range from 2 to 5 depending upon the company. For example, Peterson Farms (1988) recommends weighing a minimum of 2% of the females and 5% of the males each week from 3 wk through peak production, every two weeks up to 48 wk of age and monthly thereafter. They suggest group weighing from 3 through 4 wk of age and then individual weighing from 5 wk on. Sampling should be random and as consistent as possible. Weigh all birds penned from 4-5 locations in the house on the off-feed days. Weigh at the same time each weighing and use the same scale.

The only recent publication found on weighing

methodology was by Harms et_gl. (1984b). This study was conducted to develop a method for weighing egg-type pullets that would be faster, more accurate, and more informative than previous procedures. They concluded that weighing replacement pullets in groups of 5 was just as good as weighing individual birds. The average weight was the same if all birds penned were weighed. They utilized a 95% confidence limit to determine whether the birds differed significantly from a desired target body weight. They also used the bird-to-bird standard deviation to provide a














mathematical value to compare the variation from flock to flock. The use of sample variance in testing sample adequacy when weighing broilers was also demonstrated by Jaap (1955). Jaap recommended weighing ca. 25 birds from 3 locations in a house to estimate the average weight of a flock of broilers.
sources of Variation

Lilburn et al. (1987) reported that breeder pullets fed every day were significantly heavier at each age measured than those fed every other day, even though mean cumulative feed intake was not significantly different between restriction treatments. They noted that part of this extra body weight in the every-day treatment could be the result of feed in the crop at the time of weighing. A more recent publication (Bennett and Leeson, 1989b) comparing skip-a-day and daily feeding programs, also noted that time of weighing and feed retention in the digestive tract can strongly influence the interpretation of growth trials with broiler breeders.

Meal feeding in broilers was shown to increase variability of body weights resulting from increased variability in quantity of crop contents (May Metal-, 1988, and VWrgara et al., 1989). This finding was shown to be complicated further by environmental temperature: lower temperatures increased feed intake and variability in crop content.













Feed restriction influences total water intake as well as the cyclic patterns of water consumption (Bennett and Leeson, 1989a). These researchers reported that boredom and hunger were not the main stimuli of the cyclic pattern of water consumption associated with feeding programs; they concluded that the meal on the on-feed day had a much stronger influence on water consumption than hunger or boredom on the off-feed day. Quantities of water consumed can also be affected by diet ingredients. Patterson et al. (1989) demonstrated that water intake can be increased by as much as 1.5 times when feeding high fiber ingredients (wheat middlings) as compared to a lower fiber corn-soy diet. They also reported that the form of feed can influence water intake and showed that pelleted feed will increase water intake over mash. Birds fed high fiber diets tend to eat more feed to achieve an equivalent intake of energy than birds on a low fiber diet. This suggests that it is both the quantity of feed as well as the fiber content that leads to increased water intake.

Water consumption is also influenced by the strain of bird used in production (Ogunji et al., 1983). These researchers reported significant differences in water intake for two breeder male strains known to exhibit differences in loose droppings. They also demonstrated that dietary protein had no significant influence on water consumption. However, fecal moisture increased as dietary protein













increased. Water consumption significantly increased as dietary salt increased on feed days, but dietary salt did not influence water consumption on the off-feed days. Inherent differences in water consumption among strains of breeders make water, litter and weighing management a difficult task.

Feed and water management is also influenced by bird behavior, which in turn can contribute to problems for the weighing program. Murphy and Preston (1988) found that the duration of eating and drinking among individuals was variable.

Appleby et al. (1985) reported on a breeder hen

movement (ranging) study involving commercial flocks of ca. 4000 broiler breeders housed in deep litter. The study was conducted intensively from 22 to 33 wk of age and then at monthly intervals until 55 wk of age. They found that closely restricted ranges did not occur in either sex. Males had slightly larger ranges than females, but not significantly so. There was no consistent change in the area of the house used with age, and nesting was widely distributed throughout the house. These findings were in agreement with Craig and Guhl (1969) who reported that individuals in flocks of chickens do not use space evenly and that home ranges are either ill-defined or non-existent.














Electronic Weighing Systems

Efficient poultry production requires accurate

information and statistics that enable decision makers to act in a timely manner. This is especially true for monitoring and controlling growth and development of almost every class of poultry. An ideal weighing program would supply accurate day to day information on growth and uniformity at a reasonable cost. A variety of electronic microprocessor-based scales are currently available for almost every poultry production system and offer the potential to fulfill these needs.

Lott et al. (1982) and Stutz et al. (1984) described

the development and application of an automated weighing and analysis system for growth and efficiency studies. They noted that the prime advantages of such a system were in the reduction of transcription errors and labor requirements compared to conventional methods. Feighner et aL. (1986) reported that the implementation of a computerized weighing system resulted in a 60 to 65% savings in time over manual acquisition and use of a calculator to analyze the data. The portability of the micro-computer made it possible to transport to remote research and production areas.

Meltzer and Landsberg (1988) described the process of

recursive (continual up-dating) calculations and flexibility of modern data loggers in collecting and analyzing body weight data. Briefly, a weighing sensor (load cell)














transfers the value of a momentary load of a bird standing on it into a computerized weight indicator. The hardware contains a set of adaptive, time-varying filters used to detect exact weights of a moving, live load. Also, it can differentiate between, and adjust for, weights caused by debris left on the platform by establishing previously defined tolerance limits. The tolerance definitions are based on the known standard deviations of a normal flock plus a margin of safety. Each weighing is recorded either as an in- or out-of-range weight and is placed in its proper distribution. Pooled in-range weights are subjected to statistical processing for average and standard deviation calculations. The calculations are recursive, so that average and standard deviations are up-dated on each weighing and all output, including a distribution table and histogram, are printed on demand.

The reliability of an automatic weighing system is

limited by accuracy of readings and numbers of birds using the scale. Turner et al. (1983) found there was good agreement between automatic and manual weighings when a perch-type platform was used. Their results showed no bias by the frequent use of the perch by certain individuals to the exclusion of others. There was, however, an indication that broilers used the perch less frequently with increasing age. Newberry t al. (1985) conducted a study with roasters kept to 10 wk of age to evaluate this effect. Mean body














weights obtained on the automatic weighing system were significantly lower at 7 and 10 wk of age than those obtained manually. They attributed this result to the larger birds at later ages perching with part of their weight in contact with the floor and recommended raising the perch higher with age. Birds observed on the weighing perch on one day of the week were 3.5 times more likely to use the perch again on the following two days. Perching rate decreased from 41.6 birds/h in wk I to 4.3 birds/h in wk 10.

Blockhuis et al. (1988) reported that in broiler trials comparing manual to automatic weighing systems, the automatic (platform scale) gave a consistently lower value than weighing by hand. The difference becoming greater as the birds aged from 4 to 6 wk. A study on the behavioral response to the electronic scales made with both male and female broilers, showed that the percentage of the tagged birds that made use of the scales and the average frequency of use of the scale differed significantly with age and sex. The average frequency of use of the scale was higher for females especially at 6 wk of age. This would explain the lower average weights generated by the automatic weighing system. A possible explanation for this behavior would be the relatively lower activity of the heavier males. Between flocks there was considerable variability in the behavior of the flocks towards the weighing system. Those flocks that demonstrated higher male activity had average weights from












19
the electronic scale closer to the manual estimates for body weight and uniformity.

A recent study on filial and sexual imprinting in

precocial birds (Lavie, 1988) showed that broiler chicks raised on a commercial farm can be attached to and follow an imprinting stimuli during the rearing period. Chicks were subjected to a 3 wk imprinting process from day of age. The stimulus was comprised of plastic boxes containing a music cassette that was turned on for 10 minutes every 40 minutes through 3 wk of age in the brood area of a house. After 3 wk the boxes were placed over the full length of the house drawing imprinted birds to their new location. Relocation for the imprinted birds was significantly better than controls. This report confirmed results of an earlier study by Gvaryahu et al. (1987) who demonstrated that meat strain chicks can be attracted to an imprinting stimulus, and the imprinting object could then be used to move birds from a training area to a new location. More recently Gvaryahu et

_a. (1989) reported that filial imprinting results in reduced stress behavior and improvements in growth performance in male chicks. The implication here is the potential use of imprinting behavior on the automatic weighing systems. Blockhuis et al. (1988) began their study at 4 wk of age with no attempt at familiarizing the birds with the new scales.














pullet Rearing Period

Mortality

Lee et al. (1971) cited 63 experiments out of 80 where higher mortality was associated with feed restriction during the rearing period, and most of the increase was due to coccidiosis. Since restricted birds are known to increase litter intake (Harms et al., 1984a) and water intake (Patterson, 1989) it is not surprising that levels of mortality due to coccidiosis would be higher. However, Pym and Dillon (1974) noted that when coccidiosis is well managed, restriction levels of 60 to 80% of ad ],4itum appeared not to have a detrimental effect on rearing mortality. These researchers also showed that heat stress mortality for birds fed ad libitum was significantly higher than for restricted fed birds. They observed that during the heat stress period the more severely restricted birds moved around more freely and drank much more water than birds fed ad libitum.

Mortality levels for pullets reared on 12, 14, 16 and 18% protein diets were not significantly different for broiler breeders (Summers et al., 1967). This was in contrast to findings by Bullock et. l. (1963) and Blair, (1972) who found increased mortality among pullets fed even lower protein (10%) grower diets.














Behavior

Although feed restriction programs are currently considered essential to ensure acceptable levels of livability, fertility and hatchability, feed restriction itself can cause marked behavioral and physiological changes in growing birds. These effects can have a negative impact on flock performance. Mench and Shea (1988) found that male broiler chicks placed on a skip-a-day feeding program were more aggressive than males fed ad libitum. This display of aggression manifested more on the off-feed days than on the feed days. Competition for food is generally considered a strong stimulus for aggressive behavior. Aggressive behavior (pecking activity) was shown to be age related with peak aggression displayed between 9 and 10 wk of age. The intensity of aggressive behavior shifted from higher levels on off-feed days to higher levels on feed days by 24 wk of age.

Van Krey and Weaver (1988) showed that broiler breeder pullets provided only 45% of the recommended feeder space responded in terms of growth and uniformity as well as, or better than, those given 90% of the recommended feeder space. They noted that all semblance of social order disappears during the period of frenetic feeding immediately after food is made available. As a result, all birds are able to consume at least some feed despite very limited feeder space.












22

Studies undertaken to compare the growth and uniformity of birds reared under skip-a-day and daily feeding programs (Bennett and Leeson, 1989b) showed that body composition and flock uniformity were unaffected by feeding program. Daily feeding increased body weight gain indicating that feed is more efficiently utilized under this feeding program. Those researchers as well as Lilburn (1986) noted more aggressive feeding behavior when birds were fed daily.

Comparison trials evaluating a skip-a-day with a skiptwo-days feeding program (Bartov St al., 1988) found that body weights of birds on the skip-two-days program were significantly less, but maintained significantly better levels of uniformity than birds fed on a skip-a-day program. The decrease in body weight was also associated with a significant delay in the onset of production, however, no differences in production to 35 wk of age was detected.

nifqrmity

The importance of flock uniformity is underscored in nearly every broiler breeder management guide and poultry production book available to producers. uniformity is usually measured as the percent of the birds that weigh within � 10% of the average flock weight (North, 1984). Acceptable uniformity is when 80% of the birds are in that weight range. Relatively poor uniformity can result in a production cycle that is characterized as having a slow increase to peak production, never reaching a high peak














production, with the peak period being long and the persistency of production acceptable (Costa, 1981). In a non-uniform flock, small under-developed birds start laying much later than larger, heavier birds. This results from a relatively large spread in age at sexual maturity between early and late layers where individual birds reach maximum production at very different ages and a high peak is never achieved.

Petitte et al. (1981) reported that increased uniformity of broiler breeders could be achieved by segregation according to body weight accompanied by feeding different protein levels to each weight category. Flock uniformity measured at 20 wk of age increased from 80 to 89% by utilizing this management procedure. A more recent study with non-segregated body weight groupings by Wilson and Dale (1989) showed that accelerated levels of feed intake (163 g/bird/d) did not improve uniformity when compared to birds fed at the control level of 150 g/bird/d. Each body weight group within the flock distribution remained distinct throughout the study. This suggests that uniformity of pullet flocks at later ages can only be improved by segregation and feeding according to body weight groupings. Housing systems

Deep litter production systems in combination with

slatted platforms are widely used for broiler breeding stock to produce fertile hatching eggs by natural mating. One












24
alternative to this system for breeders is the use of cages, which necessitates the labor-intensive practice of artificial insemination. If breeder females are to be kept in cages, appropriate feeding and body weight control programs need to be developed. MoDaniel (1974) showed that broiler breeder hens generally produce more eggs when kept in cages. However, Fuquay and Renden (1980) reported that hens maintained in floor pens produced more eggs per day than hens kept in cages. In their experiment caged females had significantly higher body weights and significantly greater variation (less uniformity) in body weights than floor-reared females. Caged birds generally exhibited equivalent fertility and hatchability through 59 wk of age, although they also had higher levels of mortality than floor birds.

Petitte et al. (1982) reported that caged breeder hens had significantly heavier body weight and egg weight as compared to floor birds. Neither mortality nor cumulative production showed any difference between housing method; however, during the peak production period the caged hens exhibited significantly higher levels of production.

A follow-up study by Petitte et al. (1983) showed that the fertility of the artificially inseminated caged breeders was significantly lower than that of the naturally mated birds. Hatchability of eggs at 26 wk was not affected by housing method; however, hatchability of eggs set at 36 and












25
54 weeks of age was significantly lower for caged than floor housed hens.

Eggs from caged hens hatched significantly heavier chicks than the floor housed counterparts which was attributed to the difference in egg weight observed through the laying period (Petitte et al., 1982). Measurements on specific gravity were not reported in this study. Harms et al. (1984a) found that specific gravity of eggs from hens with access to litter was higher than hens housed on wire floors, without a significant difference in egg weight. They attributed this finding to increased intake of fecal phosphorous, calcium and other nutrients important to egg shell formation. Also, they reported that a decrease in dietary calcium resulted in increased litter consumption. It appears that caged broiler breeder hens produce larger eggs with poorer shell quality that result in a concomitant decrease in hatchability.


Pullet-Layer Tr4nsition Period

Bornstein and Lev (1982) discussed their view of the changing nutritional needs of the bird through the pulletlayer transition period in terms of flock dynamics. They concluded, until nearly all the birds in a flock have started to lay, average flock weights depend more on the relative proportion within the flock of immature pullets, prelaying pullets, and laying hens than on the weights of












26
the laying hens. Therefore, any feeding program designed to promote early egg production also enhances early average body weights, without necessarily affecting the actual weights of the laying hens. These researchers found that earlier maturity and higher egg production were associated with higher energy intake during the prelay period. The effect of increased energy during this period on egg weight was dependent on the age at which the increase in energy was provided.

McDaniel (1983) showed that quantitative differences in feed allocation during the prelay period significantly .affected shell quality and egg weight throughout production. Increased feed allocation, i.e., 176 g/bird/d, from 17 through 20 wk of age stimulated an earlier onset of production when compared to a more gradual increase in feed allocation.

Protein

Research conducted by Cave (1984b) showed that protein levels (15.4 vs. 18.1%) during the prelay period had no effect on age at 50% production, egg weight, incidence of cracked eggs, hatchability or mortality. However, the 18.1% protein treatment showed higher levels of egg production through 50 wk of age. One possible explanation of this finding relates to the important changes in the development of the reproductive system at this time (Yu and Marquardt, 1974), Cave (1984b) suggested that perhaps the higher












27

protein levels improved liver metabolism and function and/or strengthened the infundibulum which could aid in the capturing of ovulated yolks. This suggests that as the bird passes through the pullet-layer transition period a quantitative change in protein required for the development of the reproductive tract is separate from the need for body weight gain (Lilburn, 1987). Energy

A study conducted by Brake et al. (1985), investigating protein, energy and their interactions revealed that significant protein X energy interactions occurred for egg weight during wk 25 through 44, but not overall. No differences in the main effect of protein level on egg specific gravity or fertility were found.

Ingram and Wilson (1987) reported that hens fed ad

libitum for various lengths of time during the pullet-layer transition period laid at higher rates than their more restricted counterparts through ca. 43 wk of age. However, after wk 44 the hens full fed for 6 to 8 wk laid at a significantly lower rate than the more restricted birds. This was perhaps due to excessive levels of body weight gain past 40 wk which led to body weights in excess of 4.0 Kg by this time.

Robbins et al. (1988) reported that ad libitum feeding during the pullet-layer transition resulted in more eggs, but the effect was not significant. Egg weight and specific












28
gravity were significantly affected by hen age and not feed treatment.
Lihtinac Programs

An important management tool that must be considered along with a planned feeding program is an appropriate lighting program. A well managed lighting program is a cost effective way to regulate the onset of sexual maturity. The objective being the synchronization of sexual maturity, through feeding and lighting programs, with management production and scheduling needs. The normal procedure is to increase the length of the daily photoperiod from an inhibitory 6 to 12 h/d to a stimulatory photoperiod of 12 to 17 h/d, starting at point-of-lay (Morris, 1967).

Recommendations for light stimulation of breeder

pullets should be strain specific according to Cave (1984a). He found significant differences in the production response to abrupt vs. gradual increases in light stimulation for two different strains of meat-type birds. This finding was contrary to conclusions drawn by Proudfoot et al. (1980) who reported no important genotype X photoperiod treatment interaction when evaluating various abrupt and gradual lighting programs. However, Proudfoot et al. (1984) concluded that dwarf genotypes also require a different light management program than normal strains for optimum reproductive performance.













Payne (1975) reported that an abrupt increase in
photoperiod from 6 to 16 h/d had a significant effect in advancing the onset of sexual maturity when compared to a gradual 1 h/wk increase from 6 to 16 h/d. However, this procedure produced more smaller eggs than the gradual increase in photoperiod. He also found that pullets reared on a 6 h photoperiod then gradually increased to 16 h by 34 wk of age had improved reproductive performance and weighed significantly less, both at the beginning and end of the laying period when compared with pullets reared using a constant 15 h photoperiod.

Whitehead et al. (1987) also compared abrupt vs.

gradual lighting programs. The gradual program started at 18 wk of age and increased .5 h/wk to a maximum 18 h at 38 wk of age. The abrupt program began at 19 wk with a rapid increase of 1 h/wk to 26 wk then a gradual .5 h/wk increase to a maximum 17 h at 30 wk of age. The different lighting programs had no significant effect on any aspect of reproduction performance in dwarf broiler breeders.

Ingram et al. (1988) demonstrated that initiation of a stimulatory lighting program at 20 wk was superior to one initiated at 16 wk of age. Light treatments were ca. 13L:11D increased by 15 or 30 minutes to 15L:9D at 24 wk. In this experiment, lighting program had a greater effect on the more restricted (lighter body weight) group.














In two separate experiments conducted by Proudfoot et al. (1984, 1985) lighting programs were initiated at 16, 20, or 22 wk of age by abruptly increasing the photoperiod from

8 to 12 h and then further increasing the photoperiod linearly to 14 h by 23 wk of age. There were no significant overall effects on egg production, body weights or any other factor except for the number of double-yolked eggs produced and the longer delay in sexual maturity. Delaying the implementation of the lighting program also increased egg size and decreased specific gravity at 29 wk of age. They recommended photostimulation at 20 wk of age to avoid problems of lower shell quality resulting from the delayed program.

Cave (1984a) utilized two lighting programs beginning at 20 wk of age. Both increased the photoperiod from 6 to 16 h/d by either 5 abrupt increases of 2 h each week or a gradual 2 h then 1 h, then 14 increases of .5 h each week. No overall differences due to lighting program in the number of hatching eggs per hen housed could be detected. Age at 50% production was delayed significantly and egg weight was lower for the more abrupt lighting program. These researchers also reported that light intensity had no significant overall effect on any production trait, despite a rather strong change from 2 Ix to 10 Ix at 16, 20, and 22 wk of age. This response was in agreement with findings by Morris (1967).












31
The effectiveness of a lighting program is complicated by the feeding program and by seasonal differences in natural photoperiod and light intensity. Out-of-season flocks, i.e., those hatched January to May, experience delayed sexual maturity and poorer reproductive performance. Brake and Baughman (1989) studied the effect of light source and intensity during rearing for both in- and out-of-season flocks. They found that light intensity during the rearing period may need to be somewhat lower than that of the laying period in broiler breeders which are exposed to fall (decreasing natural daylight) conditions during the early phase of lay. These findings were consistent with data presented by Morris (1967) suggesting that supplemental light is most beneficial during fall and winter months of lay.

Sexual Matvrity
It is well known that restricting feed intake of broiler breeder females during the rearing period will retard growth and delay the onset of sexual maturity (Lee at al., 1971; Pym and Dillon, 1974; Watson, 1975; Leeson and Summers, 1982). When changed from restricted feeding to either an accelerated or ad libitum feeding program, various degrees of compensatory growth can occur depending upon the degree of restriction through the rearing period and the age at the change. Brody et al. (1980) showed that after severe feed restriction which delayed the onset of sexual maturity












32
well beyond a normal age, birds did not fully compensate in growth. Instead body weights remained about 25% lighter than mature body weights of the control group. When the severely restricted birds were changed to an ad libitum feeding program, sexual maturity ensued in a uniform manner. This study concluded that a minimum body weight and chronological age were required for the onset of sexual maturity.

In 1984 five papers on the subject of sexual maturity appeared, four utilizing broiler breeders and one using Japanese Quail. Soller et a-t . (1984b) demonstrated that body fat content or fat percentage alone is not sufficient to initiate sexual maturity. More importantly they concluded that there is a minimum lean body mass requirement for the onset of sexual maturity in poultry. This finding was also reported by Zelenka et al, (1984) and Oruwari and Brody, (1988) with Japanese quail.

Bornstein et al. (1984) confirmed findings of a minimum requirement for fat and lean tissue stores in conjunction with chronological age and demonstrated that these thresholds are strain specific. These researchers, as well as Pearson and Herron (1982a), reported a significant negative correlation between age and body weight at first egg.
Comparisons made by Brody et aI. (1984) between normal and dwarf strains of broiler breeders illustrated the extent














to which differences in body weight and age at sexual maturity can be affected by genetic variation. Age at first egg ranged from 153 to 173 d in normal breeders and 167 to 173 d in dwarf breeders. The greatest difference between pullets at sexual maturity and their nonlaying controls were in the size of the abdominal fat pad and the reproductive organs. This result suggests that increases in fat prior to sexual maturity, instead of being general to the carcass, are restricted to a few organs related to the partitioning of energy for reproductive performance.


Breeder Hen Laying Period
Because mature broiler breeders are capable of

consuming feed far in excess of their energy requirement for maintenance and egg production it is economically advantageous to formulate broiler breeder hen diets on a daily nutrient intake basis (Wilson and Harms, 1984). Pearson and Herron (1981) noted that broiler breeder hens are sensitive to energy intake during the breeding period. Extra dietary energy enabled birds to gain more weight (fat) and this had a depressing effect on egg production, fertility and hatchability (Pearson and Herron, 1982a; Spratt and Leeson, 1987a). Furthermore, as the rate of lay decreases, more energy is available for fat deposition so the initial negative effects on production are likely to be maintained or increased through lay.














The degree of sensitivity to energy intake is also dependent on the season of the year. Chaney and Fuller (1975) and Luther et al. (1976) reported that egg production and egg size are reduced more severely by a decrease in energy intake during the winter than during the summer, since the energy requirement for maintenance of body temperature is higher in the winter there are fewer calories that remain for egg production. These authors suggested that obesity per se does not reduce egg production since fat birds can lay at a normal rate, but the obese birds suffer from excessive mortality which results in depressed levels of hen-housed production. In addition, McDaniel et al. (1981a) and Pearson and Herron (1981) demonstrated that over-consumption of energy by broiler breeder hens adversely affected hen-day egg production, fertility, hatchability and specific gravity.

Energy

A successful feeding program based on energy

restriction demands an easily applied and practical guideline. Bornstein et al. (1979) suggested that the use of average daily weight gain as an indicator of the degree of energy restriction would be appropriate. Likewise, Pearson and Herron (1980, 1981) recommended that body weight control during egg production be considered as a criterion for assessing the adequacy of energy intake. The consequence of this recommendation was clearly illustrated













by Harms (1984) who utilized data from 49 commercial flocks to construct body weight curves along with their corresponding production curves for flocks considered to be making adequate or inadequate body weight gain. Flocks categorized as making adequate weight gain peaked at a significantly higher rate of production and maintained a rate of 80%, or above, 10 times longer (4.6 vs. .4 wk) than those with inadequate gain.
The energy restriction research conducted by Pearson

and Herron (1980, 1981) showed that the daily energy intakes of 440 to 452 Kcal ME/bird/d had higher rates of production when compared to birds fed 363 Kcal ME/bird/d. Egg weights did decrease by 1 to 4 g depending upon the protein level of the diet. This work was in close agreement with that of Waldroup and Hazen (1976) who reported that 425 to 450 Kcal ME/bird/d would maximize egg production. They also demonstrated that egg weight and body weight were directly related to caloric intake. Robbins et al. (1988) concluded that broiler breeder hens reared on a restricted feeding program and weighing ca. 3400 g at sexual maturity would require ca. 500 Kcal ME/bird/d for maximum production. This level of energy intake approximated ad libitum feeding in this experiment which may not be the case under different environmental conditions.

These higher energy values differed from findings by Spratt and Leeson (1987) who reported that 385 Kcal













ME/bird/d and 19 g of protein were sufficient to maintain normal reproductive performance of individually caged broiler breeder females through peak egg production. At 36 wk of age they noted an unexplainable accelerated decline in egg production along with a drop or no gain in body weight between 32 and 36 wk of age. This suggests that inadequate feed allocations were made at this stage and perhaps the ideal level of energy intake should be higher than the reported 385 Kcal ME/bird/d.

Research conducted by Leeson and Summers (1982)
demonstrated that excessive energy intake resulted in early maturity and reduced numbers of settable eggs. Early maturing birds gained more weight post peak than the control group even though the feed allowance was identical. This implies that over-fed birds divert feed energy to body mass rather than egg production. Peak egg production was 10% lower than standard and egg size was significantly smaller, Because obese birds have a higher maintenance requirement than lighter birds when they mature, initial egg size is smaller and often not suitable for incubation. Protein

Waldroup et al. (1976) found that the protein

requirement over the entire production period of broiler breeders raised on litter and fed a corn-soy diet without supplemental amino acids was approximately 20 to 22 g/d. Wilson and Harms (1984) revised their original













recommendations for protein and sulfur amino acid requirements (Harms and Wilson, 1980) by suggesting that nutrient specifications for broiler breeders include daily intakes of 20.6 g protein, 754 mg sulfur amino acids, 400 mg methionine, 938 mg lysine, 1379 mg arginine, 256 mg tryptophan, 4.07 g calcium, 683 mg total phosphorous, and 170 mg sodium. Pearson and Herron (1981) recommended 19.5 g/d crude protein when reared on litter and when amino acid intake was balanced. Caged breeder hens were shown by Pearson and Herron (1982b) to require 16.5 g/d protein

The absolute energy requirement associated with optimum production will depend upon the actual maintenance energy requirement which is likely to differ between cage and floor systems as well as between strains (Pearson and Herron, 1982b).

Double-Yolked Eggs

The phenomenon of multiple ovulations (double-yolked eggs) in the chicken has been reviewed by Romanoff and Romanoff (1949). Zelenka et al. (1986) noted there appears to be two major categories of multiple ovulations, sequential and simultaneous. Sequential multiple ovulations result in extra-calcified compressed-sided eggs, whereas, simultaneous multiple ovulations result in eggs with more than one yolk. Conrad and Warren (1940) reported three ways that double-yolked eggs might occur. First, 65% resulted from the simultaneous development and ovulation of two ova.













Second, 25% resulted from two ova, which were developing a day apart, being ovulated simultaneously. Third, the remaining 10% resulted from successive development and release of two ova, one remained in the body cavity for a day and was then picked up by the oviduct along with the newly released ovum. Zelenka et al. (1986) suggested that the main cause of double-yolked eggs is that two ova reach maturity and are released at the same time. They also reported on the unusual situation where two ova can develop and be released from a single ovarian follicle. They suggested that this may have resulted from two separate and distinct oocytes being encapsulated together by granulosa layer cells during the intitial stages of follicular development, or incomplete separation of oocytes following meiotic cytokinesis.

Dobbs and Lowry (1976) utilized dietary dyes to

demonstrate that, in most cases, both yolks were ovulated within 2 to 3 h of each other. Lowry et al. (1979) reported that 80% of the pairs developed at the same time and that ovulation sites were found to occur at random on the surface of the ovary.

Hormonal mechanisms that control the development of the ovarian follicular hierarchy were reported by Sharp et al. (1976) who concluded that multiple ovulation in a superovulatory line of chickens was not due to a defect in the luteinizing hormone releasing mechanism but to an abnormal













development of ovarian follicles. The inheritance of the tendancy to produce double-yolked eggs through genetic selection has been demonstrated by Lowry and Abplanalp (1967), Abplanalp and Lowry (1975), and Abplanalp et al. (1977). Williams and Sharp (1978) reported that as laying breeder hens become older, the initial decrease in egg production and the increase in egg size is a reflection of the way in which yellow yolk accumulates in a smaller number of follicles which grow to a larger size before they ovulate. Furthermore, the incidence of double yolked eggs is normally reduced to low levels as the breeder hen ages.

Christmas and Harms (1982) summarized data on 12 strains of egg-type hens to determine the influence of strain and season of the year on the incidence of doubleyolked eggs in the initial stages of lay. They found a significant strain effect on the incidence of double-yolked eggs at the onset of lay. The incidence ranged from 1.1 to 3.5% hen-day production. Spring and summer-housed laying hens produced a greater number of double-yolked eggs than did those housed in the late fall or winter months. The incidence of double-yolked eggs and age at 50% production were significantly correlated, however, it was thought to be a season rather than a within-strain maturity effect.

Feed restriction during the rearing period has been shown to limit the production of yellow follicles and the incidence of double ovulations, leading to an increase in













the number of settable eggs during this period (Fuller et al., 1969; Chaney and Fuller, 1975; Zelenka et al., 1986; Hocking et al., 1987, 1989; and Katanbaf et al., 1989b). Hocking et al. (1989) reported that feed restriction which resulted in the reduction of the number of yellow follicles at sexual maturity was associated with lighter, leaner birds with lower maintenance requirements, but delayed sexual maturity. Heavier birds were associated with higher numbers of follicles, whereas, fatter birds were associated with fewer numbers of follicles. This suggests that a positive relationship exists between ovulation rate and lean tissue mass. These authors recommend that feed restriction should be continued to point of lay.

















CHAPTER III
TOWARDS AN APPROPRIATE STRATEGY FOR WEIGHING
BROILERS, BROILER BREEDER PULLETS AND BREEDER HENS ON-FARM


Introduction

The ability to estimate average body weight and flock uniformity accurately is an important part of breeder and broiler managers' duties. Average body weight estimates of commercial flocks are used constantly to evaluate breeder growth and development relative to a particular strain's standard. Decisions concerning the proper feed allocation required to consistently achieve a target body weight objective over a period of time are based on these estimates and any error in their accuracy will be reflected in the inefficient growth and production of the flock. Also, decreases in flock uniformity, i.e., increased variation in body weight, is a sign of suboptimum husbandry conditions, the cause of which must be identified and corrected in a timely manner or production inefficiencies will persist or worsen.

An appropriate weighing program is an important process that assures the maintenance of technical and economic efficiencies in the pullet and breeder houses as well as the













processing plant. A weighing program is considered appropriate for a particular attribute (mean body weight and flock uniformity) in a particular field condition (restricted or full fed) if it satisfies several conditions. First, the accuracy of the estimated attribute must be as good as, or better than, a level required to achieve an objective. The objective in this case is to determine the best nutrient allocation or other management decision necessary to achieve body weight and uniformity standards. Secondly, the cost of conducting a weighing program must be within the practical limits of resources available.

A review of the various management guides published by the breeder companies confirms the lack of consensus concerning suggested weighing procedures. Recommendations range from weighing 1, 2, or 3% of the flock to sampling 2, 3, or 4 locations in a house. Furthermore, none of the management guides quantify for the breeder manager what level of technical or economic inefficiency will result if the procedures are not followed.

There has been little or no research conducted on weighing procedures that maintain a practical level of accuracy of the weigh data while minimizing the cost of collecting those data.

The objective of this study was to establish general guidelines for the development and implementation of an appropriate weighing program. Specifically, the objectives













of Experiment 1 were to quantify the cyclic nature of body weight gain in a 48 h period and to demonstrate the degree of error in estimating gain when weighing programs are not scheduled at a consistent time interval. The objectives of Experiment 2 (on-station) and 3 (on-farm) were to determine the effect of scale type, sample units (individual vs. group), sample size, sample location, time of sampling, and complexity of procedures used in the on-farm weighing of broilers, broiler breeder pullets and breeder hens on average body weight gain and uniformity.



Materials and Methods

Experiment 1

Trials 1 and 2. Eight pens containing 16 Arbor Acres broiler breeder females, 25 wk old and not yet in production, were divided into two feeding programs. The first, an early feeding time (ERL) allocated 122 g of feed/bird/d at 0430 h and the second, a late feeding time (LTE) allocated an equivalent amount of feed at 1530 h. Each feeding program consisted of two groups of two pens each with a significant difference in average body weight between groups. These weight class groupings (trials) could then simulate different houses or farms and the effect of initial body weight evaluated. Each pen was weighed, eight birds per crate (two crates per pen), at 2 h intervals starting at 0430 h and ending at 2030 h on the first day,











44
with the same procedure repeated the following day. Crated birds were weighed on an electronic scale (Detecto, model EF-218-56) with a gross capacity of 90.7 kg (200 lb) and a precision of 45 g (0.1 Ib). The four crate weights for each trial were pooled and the average body weight and change (gain or loss) for each time period calculated. Experiment 2

Trials 1, 2 and 3. Three weight class groupings,

totaling 274 Arbor Acres broiler breeder females, 41 wk old and near peak production, were used to test the accuracy of different types of scales (electronic vs. mechanical) and sample units (individual vs. group) in determining average body weight and uniformity. Three groupings (trials) were used to simulate body weight conditions found on different farms. Each trial consisted of six pens containing ca. 15 adult breeder hens. Birds were crated seven or eight birds to a crate depending upon the population size within a pen.

The weigh routine was as follows: crate weights (GRP) were measured on an electronic Detecto scale to the nearest 45 g; birds were individually (IND) removed from the crate and weighed, first on an electronic (ELC) scale (Weltech, model BW-1) to the nearest 1.0 g and then on a mechanical (SPR) spring scale (Salter, model 235) to the nearest 45 g. All weighings were conducted by the same person and data recorded by a technician to expedite the flow of procedures.













Experiment 3 (on-farm)

General procedures. A catching pen was used to pen-up a sample of birds as large as possible without causing excessive piling. Samples were measured at two locations in each on-farm house with each house considered a trial. The first location was along the side wall near a feed dump (FDD). The second, an end location (END) was along the side wall at the end door. Birds were weighed individually on a mechanical SPR scale. Birds in the first pullet house only were weighed individually on the ELC scale to validate earlier findings concerning type of scale used.

Weighing procedures were as follows. The weigher

selected and weighed individual birds from the penned-up sample. A subjective decision was then made to note all grossly under- or overweight birds as suspected outliers. This process continued until a predetermined fixed quantity of bird weights (N=60) was achieved and the last weight noted. Weighing was then continued until all remaining penned birds were weighed. All recorded weights were tabulated under the following treatments: fixed quantity with suspected outliers included (FXD); fixed quantity with outliers removed (FXO); and all birds penned including suspected outliers (PND). Two weeks after the initial weighing these procedures were repeated in the morning (AM) for Trial 1 and 2, and afternoon (PM) for Trial 1 only. Follow-up time of AM weighing was within one hour of the












46
initial weigh time and PM weighings were approximately five hours after AM weighings.

Pullet farm. Two dark-out houses (Trials 1 and 2)

containing ca. 14,500 replacement pullets were sampled when

8 and 10 wk old on the off-feed day during a skip-a-day feeding program. Birds were fed at 0700 h and water was restricted in the afternoon. Each house was equipped with pan type feeders and nipple drinkers.

Breeder farm. Samples of birds were weighed in two

curtain-sided breeder houses (Trials 1 and 2) containing ca. 7,350 adult breeder hens 36 and 38 wk old and in their tenth and twelfth week of production. Hen-day production was about 74% at that time. Females ate from chain feeders and drank from bell-type waterers, while males ate separately from pan feeders.

Broiler farm. Body weight measurements were made in three curtain-sided broiler houses (Trials 1, 2, and 3). The first was recently built and equipped with nipple drinkers, pan feeders and contained ca. 24,500 straight-run broilers 40 d old. The other two were older houses and were equipped with cup drinkers, pan feeders and each contained ca. 14,500 straight-run broilers 38 d old. Statistical Analysis

The TTEST procedure of SAS/STAT (1985) was used to calculate means for a particular variable under investigation, and then to test the hypothesis that the











47
means of two groups of observations were equal. The F-test ratio of sample variance (Montgomery, 1984) was used to test the hypothesis that the variance of two groups of observations were equal. Differences between groups of observations were considered significant if P < .05.



Results and Discussion

Experiment 1

Time of weighing. Initial body weights prior to

feeding on the first day were 2582 and 2676 g for Trial 1 and, 2747 and 2727 g for Trial 2 (Table 3-1). Change in body weight (gain or loss) data from the pooled trials (Table 3-1) demonstrate (Figure 3-1) how birds on the LTE program reached a 205 g peak change in body weight in 3 h after feeding, which was greater than the 155 g peak change in the ERL program which also occurred at 4 h after feeding. Birds on the LTE program lost weight, starting from peak body weight and ending just prior to feeding, at the rate of 8.6 g/h while the rate for the ERL program was slower at 7.1 g/h. These differences in feeding programs suggest that birds on a LTE program may require greater quantities of water. The higher level of gain due to possible increased water intake could explain the greater mass lost over this time period. This finding also suggests that water restriction should not begin for at least 4 h after birds have finished eating.













Figure 3-2 clearly illustrates the cyclic changes in body weight over a 40 h period when fed on an ERL schedule. Any change from the initial time of weighing to the followup weighing will create an error in the estimated gain. For example, an initial weighing at 0830 h followed by a weighing the second day at 0830 h resulted in a 22 g increase while a weighing at 1030 h will have a potential error of 7 g by showing a gain of 15 g. If the birds are weighed on the follow-up day in the afternoon at 1430 h the estimated change in body weight is a loss of 27 g, or a difference of 49 g from 0830 to 1430 h. The true gain for the first 24 h period was 14 g, which was measured from just prior to feeding (0430 h) on day one, to just prior to feeding on the second day. This would suggest that weighing just prior to feeding would be the most effective procedure in evaluating gain which is in agreement with findings by Turner et al., (1983). The drawback to this procedure with feed restricted birds is the almost frenetic behavior of the birds at this time that could cause accidental mortality. Breeder company suggestions to weigh at noon or ca. 3 to 4 h post-feeding would find the birds at their greatest level of feed and water intake. Body weights could be rising or declining at this time, along with the possibility of significant variation in body weights caused by vomiting. Furthermore, afternoon hours for weighing should be discouraged in the summer to avoid stressing the birds













during the hours of highest temperatures. An ERL feeding schedule coupled with an evening weigh program is one logical alternative; birds have settled down, voided most feed, water and eggs, and temperatures are cooler. In this scenario, variation in body weights as well as undue stress could be minimized at no additional cost to the program.


Experiment 2

Scale type. Average body weight estimates measured on the SPR scale were numerically higher but not significantly different from measurements made on the ELC scale (Table 32). The on-farm validation of these findings was upheld in Experiment 3. An observation noted during these experiments was that the automatic printing feature of the ELC scale decreases the possibility of a transcription error and the time (cost) necessary for weighing.

Sample unit. All trials conducted on-station

demonstrated that the average body weight determined by individually weighing birds was not significantly different than group weighing with crates of seven or eight birds (Table 3-2). However, the estimates of flock uniformity as measured by the standard deviation (SD) among observations was significantly greater and more representative of the true flock uniformity, when birds were weighed individually.













Experiment 3 (on-farm)

Location Effect

Straight-run broilers. Body weight and body weight

uniformity estimates for the FDD and END house locations are presented in Table 3-3. In general, broiler weights and flock uniformity were not found to be different between locations. There was a significant difference in average body weight in Trial 3, which was attributed to the chance occurrence of a slightly higher ratio of males sampled at the FDD location at that particular sampling.

Pullets. Average body weight was not found to be

different between locations in either trial or at the ages tested (Table 3-4). This observation would tend to be consistent with findings of Van Krey and Weaver (1988) in which it was shown that all semblance of social order disappears during the period of frenetic feeding. Significant differences in uniformity were found at the two locations in trial one at 8 and 10 wk of age. The greater variation at the FDD location was attributed to including suspect outliers in the sample. Removal of these observations on the basis of their being true outliers, as shown in Table 3-7, resulted in levels of uniformity at both locations that were no longer significantly different.

Breeders hens. A statistical difference in average

body weight of breeder hens due to house location was found in Trial 1 at 36 and 38 wk of age without there being a













difference in uniformity (Table 3-5). However, the END location was greater at 36 wk while the FDD was greater at 38 wk. Furthermore, the 38 wk, PM weighing failed to detect differences in location suggesting that the END location actually gained weight during the day by feeding and drinking later. Perry et al. (1971) noted that after laying, a period of feeding and drinking followed, which suggests earlier laying by the END location. Trial 2 does not substantiate these findings. No significant differences in average body weight or uniformity between locations were detected for any PND sample. It is difficult to determine from these data if the differences found in Trial 1 at the various ages were due to changing flock dynamics or sampling error. Consistency in the uniformity data as well as the low number of detected outliers suggests that there could be significant behavioral differences at various locations in the house. Appleby et al. (1984) found considerable movement of both males and females throughout the house. However, their study was conducted in buildings 46 m long, whereas these data were collected in buildings 122 m in length.

Time of weighing. The importance of consistently weighing at the same time each scheduled weighing (Experiment 1) is underscored with breeder pullets and laying breeder hens. Two principal observations can be made from the data presented on both AM and PM weighings in













Tables 3-4 and 3-5, which are evaluated and presented in Table 3-6. First, the measurement of average body weight gain of the pullets decreased by ca. 10 g/h between the AM and PM weighings, despite the fact they were off feed. This was determined from Table 3-6 where the difference in pullet body weight from AM to PM at 10 wk (Trial 1) ranged from a loss of 43 g to 67 g over the 4 h period. Secondly, average body weight gain data for the adult breeder hens were not as conclusive. Birds in the FDD location gained weight over the two week period in both Trial 1 (66 and 77 g) and Trial

2 (141 and 142 g), however they lost weight (-8 and -35 g) between the AM and PM weighings in Trial 1. This was in marked contrast to birds weighed at the END location which lost considerable weight (-141 and -159 g) over the two week period but gained back nearly 25-30% of it (36 and 60 g) between the AM and PM trials. The principal conclusion being that flock dynamics in the breeder house contribute to a complex situation where relatively radical changes in body weight occur throughout the day. This is especially true during the morning hours when feeding, drinking and laying are all contributing to variation in body weights.

Outliers. Information required to determine if a

grossly under- or overweight bird should be rejected as a true outlier to the normal body weight distribution is presented in Table 3-7. No true outliers were detected in the straight run broiler flocks. Half of the suspected













outliers in the breeder flocks were true outliers and their inclusion in flock uniformity estimates could confound interpretations. In the pullet flocks five out of 41 suspected outliers were classified as true outliers. Three of the five were missexed males and two were either sick or starve-outs.

Sample size. The average body weight and uniformity

measurements for FXD quantities of breeders and pullets were not significantly different than PND quantities (Table 3-4). Figure 3-3 illustrates the effect of a weigh procedure that prescribes weighing a fixed quantity of birds, i.e., 60 pullets while rejecting suspected outliers (A) on the frequency distribution of confidence intervals. Compared to this procedure is a distribution of confidence intervals that resulted from weighing all pullets in a penned-up sample (B). The greatest number of suspected outliers in a pullet flock were, by far, under-weight birds. Therefore, rejection of these observations would tend to inflate the mean body weight. Rejection of the extremes of a distribution, i.e., grossly under- and over-weight birds may lower the level of sample variance which may therefore deviate from the true population variance. By weighing all birds in the penned-up group it should be possible to have more confidence that the mean estimates the true population mean.












Sample size relative to flock size was determined by sequentially adding 10 pullets or 20 breeders to their respective samples, while evaluating the change in variance as measured by the standard deviations, Table 3-8. A stabilized level of sample variance would indicate that the sample size achieved a level where additional observations would not change the estimate of the population variance. The sample variance peaked with a sample size slightly under one percent of the population for the straight-run broilers and pullets tested in these trials. Estimated sample variance in a breeder flock peaked at only 0.5% of the population. These levels of peaked variance would define an absolute minimum sample size that could be used to estimate flock body weight and uniformity.

It is known that the statistical accuracy of a sample estimate generally increases with the sample size as a percent of the flock size, number of sampling locations selected per house, and the complexity of the sampling procedures used. However, an increase in the sample size, and/or number of locations will increase the cost of weighing and disrupts the flock. Therefore, the choice of an appropriate method of weighing broilers, broiler breeder pullets, and breeder hens is primarily concerned with maintaining the proper balance between the sample size and number of locations that achieve a minimum cost without













sacrificing an adequate level of accuracy for the decision making process.

In summary, this study demonstrated that the required balance between accuracy and efficiency of an appropriate weighing program could be maintained if average body weight and flock uniformity estimates were derived from one convenient location, weighing all birds in a penned-up sample, a number of penned-up samples with a total bird count approximating at least one percent of the flock size, and weighings conducted at the same time each weigh period.

Those elements of a comprehensive weighing program that have the greatest impact on the level of accuracy of the estimate, but do not add appreciably to the total cost of data collection, e.g., time of weighing, should certainly be given the greatest consideration.














TABLE 3-1. Effect of feeding time (ERL vs. LTE) and time of day on non-laying broiler breeder female mean body weight and weight change (Exp. 1)

ERLa LTEa
Trial lb Trial 2 Pooled Trial 1 Trial 2 POOLED
Time BWT Change BWT Change BWT Change BWT Change BWT Change BWT Change
Day (h) (g) (g) (g) (g) (g) (g) (g) (g) (g) (g) (g) (g)

1 04:00 2582c NA 2747c NA 2664 NA 2785 NA 2818 NA 2801 NA
04:30 FEED FEED FEED
06:30 2723 140 2864 118 2794 129 2774 NA 2806 NA 2790 NA
08:30 2755 173 2884 138 2820 155 2754 NA 2792 NA 2773 NA
10:30 2737 155 2883 136 2810 145 2724 NA 2774 NA 2749 NA
12:30 2725 143 2872 125 2798 134 2708 NA 2754 NA 2731 NA
14:30 2701 119 2842 95 2772 107 2676c NA 2727c NA 2701 NA
15:30 FEED FEED FEED
16:30 2670 88 2816 70 274 79 2839 182 2889 176 2864 179
18:30 2670 88 2806 60 2738 74 2870 213 2910 197 2890 205
20:30 2647 65 2795 48 2721 57 2859 202 2896 183 2877 192

2 04:00 2601 19 2755 9 2678 14 2794 118 2822 95 2808 106
04:30 FEED FEED FEED
06:30 2747 165 2896 150 2821 157 2785 110 2815 88 2800 99
08:30 2769 188 2916 170 2842 179 2767 91 2813 86 2790 89
10:30 2772 191 2899 153 2835 172 2745 70 2802 75 2774 72
12:30 2750 168 2881 135 2816 152 2720 44 2779 52 2750 48
14:30 2727 145 2859 113 2793 129 2694 19 2757 30 2725 24
15:30 FEED FEED FEED
16:30 2700 118 2835 89 2767 104 2779 104 2832 105 2806 104
18:30 2679 97 2818 72 2748 84 2874 199 2910 183 2892 191
20:30 2663 81 2806 60 2735 71 2879 203 2900 173 2889 188

aERL= Early feed time (0430h); LTE= Late feed time (1530 h); NA=Not applicable. bTrial 1 and 2, average of two pens.
cInitial body weight prior to feeding.














TABLE 3-2. Effect of scale type (ELC vs. SPR) and sample unit (IND vs.GRP), on mean adult breeder hen and breeder pullet body weight and uniformity (SD), (Exp. 2)

Age Trial Scale type Sample unit

(wk) No. ELC SPR Sig. IND GRP Sig.

38 1 N , no. 90 90 90 12
mean, g 4029 4063 NS1 4029 4074 NS
SD, g 399 399 NS2 399 196 *

38 2 N , no. 90 90 90 12
mean, g 3781 3811 NS 3881 3874 NS
SD, g 336 331 NS 336 152 *

38 3 N , no. 94 94 94 12
mean, g 3597 3624 NS 3597 3644 NS
SD, g 319 322 NS 319 125 *

40 1 N , no. 90 90 90 12
mean, g 4036 4063 NS 4036 4053 NS
SD, g 415 419 NS 415 191 *

40 2 N , no. 89 89 90 12
mean, g 3816 3842 NS 3816 3797 NS
SD, g 361 360 NS 361 237 *

40 3 N , no. 94 94 94 12
mean, g 3635 3663 NS 3635 3632 NS
SD, g 320 325 NS 320 289 *

8 4 N , no. 111 111
mean, g 844 855 NS
SD, g 130 133 NS --- --8 5 N , no. 107 107
mean, g 862 847 NS
SD, g 101 97 NS


1 t-test on sample means ( 2 F-test ratio on sample v ELC= Electronic scale SPR= Spring scale IND= Individually weighed GRP= Group weighed


P<.05).
variance (P<.05).
SD= Standard deviation
Sig= Significance (P<.05)














TABLE 3-3. Effect of sample location (FDD vs. END) and sample type (PND vs. FXD) on mean straight-run broiler body weight and uniformity (SD),(Exp. 3)

Age Trial Pop. Sample Location
(d) No. Size Type FDD END Sig. Pooled

40 1 24,500 PND N, no. 70 78
mean, g 1683 1663 NS1 SD, g 198 199 NS2

PND N , no. 81 87
mean, g 1674 1708 NS SD, g 206 232 NS


All N , no. 151 165 316
mean, g 1678 1687 NS 1683 SD, g 202 217 NS 210

FXD N , no. 50 --mean, g 1670 --SD, g 211 --38 2 14,500 PND N , no. 100 65 165
mean, g 1562 1551 NS 1558 SD, g 199 173 NS 189

FXD N , no. 50 --mean, g 1623 --SD, g 228 --38 3 14,500 PND N , no. 80 86 166
mean, g 1665 1564 * 1613 SD, g 194 196 NS 201

FXD N , no. 50 --mean, g 1566 --SD, g 212 ---


It-test on sample means (P<.05). ZF-test ratio on sample variance FDD= Feed dump location END= End location PND= All birds penned FXD= Fixed quantity


(Ps.05).
SD= Standard deviation Sig= Significance (P<.05)














TABLE 3-4. Effect of sample location (FDD vs. END) at various ages and by sample type (PND vs. FXD) on mean pullet body weight and uniformity (SD), (Exp. 3)

Trial 1 Trial 2
Age Location Location
(wk) Time Type FDD END Sig. FDD END Sig.

8 AM PND N , no. 111 107 113 100
mean, g 855 847 NS 854 873 NS
SD, g 133 97 * 129 131 NS

FXD N , no. 60 60 60 60
mean, g 890 862 NS 866 884 NS
SD, g 142 97 * 131 133 NS

10 AM PND N , no. 92 72
mean, g 991 1033 NS 1022 1033 NS
SD, g 146 140 NS 156 159 NS

FXD N , no. 60 60 60 60
mean, g 1031 1050 NS 1032 1027 NS
SD, g 138 134 NS 167 163 NS

10 PM PND N , no. 88 96 --- --mean, g 948 974 NS --- --SD, g 168 145 *--- --FXD N , no. 60 60 --- --mean, g 974 984 NS --- --SD, g 162 143 NS --- --t-test on sample means (P<.05)
2 F-test ratio on sample variance (P.05). FDD= Feed dump location SD= Standard deviation
END= End location Sig= Significance (Ps.05)
PND= All birds penned FXD= Fixed quantity















TABLE 3-5. Effect of sample location (FDD vs. END) at various ages and by sample type (PND vs. FXD) on mean breeder hen body weight and uniformity (SD), (Exp. 3).

Sample gIAL k TRIA 2
Age/Time type FDD END Sig. FDD END Sig.

36 wk/AM PND N , no, 69 69 77 70
mean, g 3291 3387 * 3342 3388 NS
SD, g 241 268 NSZ 310 326 NS

FXD N , no. 60 60 60 60
mean, g 3296 3385 * 3337 3412 NS
SD, g 252- 261 NS 295 330 NS

38 wk\AM PND N , no. 64 -64 64 64
mean, g 3356 3245 * 3482 3403 NS
SD, g 356 300 NS 326 292 NS

FXD N, no. 60 60 60 60
mean, g 3373 3240 NS 3478 3395 *
SD, g 356 300 NS 362 298 NS

38 wk\PM PND N , no. 62 62
mean, g 3348 3281 NS .
SD, g 320 268 NS

FXD N , no. 60 60
mean, g 3338 3286 NS SD, g 321 271 N-S


t-test on sample means 2F-test ratio on sample FDD= Feed dump location END= End location PND= All birds penned FXD= Fixed quantity


(PIs.05).
variance (Ps.05).
SD= standard deviation
Sig= Significance (P,.05)














TABLE 3-6. Effect of sample breeder hen and pullet body


Sample Age interval type (Age, wk; Time)


location (FDD vs. weight gain (Exp.


Trial 1 FDD END
(g) (g)


END) on mean 3)


3)


Trial 2 FDD END
(g) (g)


Breeder hen PND (36;

FXD (36;


AM) AM)


to (38; to (38;


AM) AM)


-141

-159


(36; AM) to (38; PM) 58 -105

(36; AM) to (38; PM) 42 -99

(38; AM) to (38; PM) -8 36

(38; AM) to (38; PM) -35 60


t


(8; ( 8;


AM) AM)


to (10; to (10;


AM) AM)


135 141


186 188


( 8; AM) to (10; PM) 92 127

( 8; AM) to (10; PM) 84 122

(10: AM) to (10; PM) -43 -5q ---


(10;


AM)
AM)


(10;


PM)
PM)


-56


-67


1 Age interval= 36 wk of or PM weighing. FDD= Feed dump location END= End location PND= All birds penned FXD= Fixed quantity


age AM weighing to 38 wk of age AM

SD= Standard deviation
Sig= Significance (P<.05)


141 142


16

-16


PND FXD PND FXD

Pulle
PND FXD


PND

FXD PND FXD


167 167


160

143














TABLE 3-7. Classification of suspect outliers as true outliers by testing mean body weight with an outlier interval (� 3*SD) for broilers, pullets and breeder hens (Exper. 3)

Outlier
Trial Mean 3*SD Interval Suspect Actual
(no.) Age N (g) (g) (g , g) (no.) (no.)

Broilers

1 40 d 316 1683 629 (1054, 2312) 4 0

2 38 d 165 1556 566 ( 990, 2122) 1 0

3 38 d 166 1615 603 (1012, 2218) 1 0


Breeder hens

1 36 wk 138 3339 776 (2563, 4115) 0 0

2 36 wk 147 3373 896 (2477, 4268) 2 2

1 38 wk 128 3300 998 (2303, 4298) 2 1

2 38 wk 128 3443 980 (2462, 4423) 4 1

Pullets

1 8 wk 218 851 350 ( 501, 1202) 7 2

2 8 wk 213 863 390 ( 473, 1252) 9 0

1 10 wk 164 1009 434 ( 575, 1444) 12 0

2 10 wk 162 1026 471 ( 555, 1497) 13 3














TABLE 3-8. Effect of sample size on mean and variance of body weight for broilers, pullets and breeder hens.

N Mean SD N Mean SD

Breeder hens

10 3560 233 10 3451 194
20 3465 301 20 3363 244
30 3433 382 30 3391 249
40 3394 360 40 3386 291
50 3411 343 50 3373 275
60 3414 333 60 3385 261
70 3387 326 70 3390 268
80 3384 316 80 3378 257
90 3387 305 90 3368 256
100 3387 297 100 3339 265
110 3357 318 110 3344 261
120 3353 309 120 3347 261
130 3364 312 130 3344 270
140 3364 320 140 3338 259

Broilers Pullets

20 1707 161 20 870 123
40 1718 187 40 889 126
60 1702 198 60 885 113
80 1693 195 80 866 112
100 1687 201 100 862 111
120 1690 198 120 855 132
140 1693 201 140 859 128
160 1685 199 160 857 124
180 1680 200 180 860 119
200 1683 202 200 861 116
220 1683 212 220 853 117
240 1689 212
260 1690 211
280 1692 206
300 1676 206




















2.85 2.83 2.81 2.79 2.77 2,75 2.75 2.73


0 :3 0 00 :30 I: O :3 30 : 06:30 i0 30 i14:30 1:o30

TIME PERIODS


FIGURE 3-1. Effect of early feeding schedule and time of weighing on broiler breeder female body weight (Exp. 1).


20- A N AAA

05:30 10:30 14:30 19:30 22:30 02:30 06:30 10:30 14:30 18:30 SEARLY FEED SCHEDULE T ME PER I ODS + LATE FEED SCHEDULE


FIGURE 3-2. Cyclic changes in non-laying breeder female body weight, on an early or late feeding schedule.














1.06


1.04


1.02


1.00


0.98 0.96 0.94


0.92


50%


70%


_________


90%


FIGURE 3-3. Frequency distribution of confidence intervals for a fixed quantity of birds excluding outliers (A) and all birds penned-up in a flock (B)


-


CONFIDENCE INTERVAL, %

















CHAPTER IV

THE EFFECT OF SEVERE FEED RESTRICTION
DURING THE REARING PERIOD ON FEMALE
BROILER BREEDER REPRODUCTIVE PERFORMANCE




Introduction

Early studies that examined the effect of feed

restriction on reproductive performance utilized ad libitum feeding as the bench mark or control group in their experimental designs. A generalized model illustrating this effect was proposed by Bullock et al. (1963), where they postulated that the only response to restricted feeding is a delay in sexual maturity, characterized by the displacement or shifting of the production curve to older ages. Since then, numerous research projects have shown that relative to ad libitum controls, feeding programs that restrict the feed intake of broiler breeder females during rearing will delay sexual maturity (Lee et al., 1971; Harms et al., 1979; Leeson and Summers, 1982), increase initial egg size (Blair et al., 1976; Leeson and Summers, 1982), decrease the number of doubled-yolked eggs and therefore increase the number of settable eggs (Fuller et al., 1969; Chaney and Fuller, 1975; Christmas and Harms, 1982; Hocking et al., 1989; Katanbaf et













al., 1989b), increase livability (Lee et al., 1971; Wilson and Harms, 1986, Katanbaf et al., 1989a), increase fertility and hatchability (McDaniel et al., 1981b; Bilgili and Renden, 1985), and improves egg production (Leeson and Summers, 1982; McDaniel, 1983; Wilson and Harms, 1986; Hocking et al., 1987; Katanbaf et al., 1989b). These effects will also be influenced by photoperiod, temperature and other environmental factors that can alter the reproduction process.

The primary breeder companies currently recommend

various degrees of feed restriction for their particular strain which permit a relatively narrow range of growth curves to be followed in different environments. The optimality of these prescribed standards are of issue and raise interest in feed allocations below current recommendations (severe restriction).

If the overall objective of the breeder manager is to maximize the number of placeable chicks per hen housed over a normal production period, then the optimal growth curve and corresponding feeding program for a particular strain must be identified. The growing consensus is that current recommendations lead to an overweight breeder flock that does not meet this objective.

Therefore, the overall objective of this experiment was to evaluate the breeder's recommended growth curve by determining the relationship between various degrees of













severe feed restriction (relative to breeder recommendations) and subsequent effects on the more specific evaluation criteria: body weight, sexual maturity, mortality and other hatching egg production parameters that impact on the production of placeable chicks per hen housed.


Materials and Methods
Stock and Management

Male and female Arbor Acres strain broiler breeders,

hatched in-season at a commercial hatchery (September, 1987) and vaccinated for Marek's disease before placement were used in this experiment. A total of 860 day-old female chicks were randomly placed into 20 litter-floor pens of an open-sided house. Each 3.1 X 3.6 m pen was equipped with an automatic waterer for ad libitum drinking and three pan type feeders. Male chicks were group reared separately in a litter-floor pen of an open sided-house and fed according to breeder recommendations. At 20 wk of age all males were individually weighed and 60 males, weighing between 2650 and 2950 g, were randomly placed 3 per female pen. Sixty replacement males (12 per treatment) were randomly placed in pens in a separate house and maintained on respective feed treatments. All birds were beak trimmed and vaccinated for fowl pox at 10 d of age. Birds were vaccinated for Newcastle disease and infectious bronchitis at 2, 5, 12, and 15 wk of age, and avian encephalomyletitis and fowl pox at














10 wk of age. Chicks were reared under natural daylight conditions until 20 wk of age, then daylength was abruptly increased from ca. 12 h to 15 h by supplementing with incandescent light, ca. 22 lux at bird level, from 0430 h to 1930 h, E.S.T.

Feed Treatments

Birds were fed ad libitum until 2 wk of age and

restricted daily during the third week on a starter diet (Table 4-1). All birds were fed on a skip-a-day basis a 16% grower diet from 4 through 8 wk, a 12% grower diet from 9 through 15 wk, and a 16% grower diet from 16 through 19 wk of age. Five feed treatment groups based on a standard feeding program were used. The feed treatments were designed to have body weight follow growth curves over the life cycle that were: 8 percent above the breeder recommended standard curve (+8%); standard (STD), which approximated the breeder's standard curve; and 8 (-8%), 16 (-16%) and 24 (-24%) percent below the standard curve. Feed allocations for the STD treatment were derived from average weekly body weight estimates and all other feed treatments adjusted quantitatively. Daily feeding of a laying diet began at 20 wk of age, where the nutrient intake, other than energy provided per bird per day, was based on current recommendations (Wilson and Harms, 1984). This intake furnished for the STD treatment 20.6 g protein, 754 mg sulfur amino acids, 4.07 g Ca, 683 mg total P, and 170 mg













Na, per bird per day (Table 4-2). Adjustments in diet formulation and allocation were made weekly based on level of body weight gain and egg production. PrqdUction Measurements
Egg production and mortality records were kept daily.
Egg production was summarized by phase of maturity, that is, pullet (1 d to 5% production) or breeder hen (5% production to 65 wk of age). Average body weight was determined weekly for each pen by weighing four groups of ca. 8 females and one group of 3 males through 45 weeks and then bi-weekly until 62 weeks of age. Average body weight of the STD treatment was compared with a target body weight recommended by Arbor Acres for a particular age, and a feed allocation made. Feed allocations for all other feed treatments were quantitatively adjusted from this allocation to STD.
Eggs were collected three times daily, classified as
double-yolked or normal and stored in an egg cooler at 13 C. Production was recorded daily and summarized by 14 d periods. Average egg weight was determined weekly by individually weighing all normal eggs from one day's production. Specific gravity was determined once per 4 wk period, from 30 through 62 wk of age, by weighing eggs individually then, storing one day's egg production overnight and the next morning using the saline flotation method with solutions set at intervals of 0.0025 g/imL Fertility and hatchability were determined every 4 wt from













32 to 64 wk using four days production, ca. 100 settable eggs, from each pen and set according to normal incubation procedures.

Research Period and Environment

The relationship of average weekly temperature (highs and lows), and hours of daylight to the research period is illustrated in Figure 4-1. Birds were hatched in September, 1987 and commenced production in early March, 1988. The onset of production coincided with increasing temperatures and hours of natural daylight. Experimental Design and Statistical Analysis

The experimental design was a randomized complete block of five pens replicated 4 times and containing 36 female and

3 male broiler breeders from 28 wk until termination (less female mortality). The experimental unit was the pen. Forty-three females were started in each pen with seven females removed for analysis of physical attributes by 28 wk of age. The five feed treatments were replicated four times into blocks that minimized experimental error caused by temperature or natural daylight gradients within blocks while maximizing their effects among blocks. Data analysis utilized a linear statistical model for a randomized complete block design:

Yijk = U + Ti + B + Eijk
where U = overall mean; Ti = fixed effect of feed treatment and i = 1, 2, .5; Bj = fixed effect of pen blocking and












72
j = 1, 2, .4; and Ejik = residual effect. When differences among treatments were obtained, comparisons among means were made by using the Waller-Duncan K-ratio test and were considered significant if P < .05 (SAS, 1985). Data on flock uniformity were analyzed using the general linear models procedure (SAS, 1985). Differences in flock uniformity were evaluated by the F-test ratio of variances. Pearson's product-moment correlations were determined between hatchability and fertility, and between specific gravity and egg weight as a measure of linear association (SAS, 1985).



Results and Discussion

Body Weiqht and Uniformity

Growth of the STD fed birds throughout the rearing and breeder periods approximated the growth curve recommended by Arbor Acres, the primary breeder (Figure 4-2). Growth curves resulting from all other feed treatments paralleled STD through 62 wk of age. Some convergence in body weight during the latter half of the production cycle did occur especially between the -24% and -16% treatments. As expected, the effect of feed treatment on mean body weight at 20 wk of age was significant (Table 4-3) with the -24% birds being 520 g lighter than STD. Uniformity, as measured by the coefficient of variation, was significantly better for the -8% treatment only. A possible trend towards poorer













uniformity for the most restricted birds was suspected but not substantiated. Blair et al. (1976) and Lee et al. (1971) reported that an apparent disadvantage to feed restriction was a possible negative effect on flock uniformity. The effect of feed treatment on mean body weight was still significant through 62 wk of age and the

-24% treatment maintained a mature body weight 255 g lighter than STD. This was similar to findings by Brody et al. (1980) who showed that after severe feed restriction, body weights remained about 25% lighter than the mature body weights of a control group. Uniformity at 62 wk improved from 20 wk levels indicating that body weight distributions seem to stabilize as the flock achieves a mature body weight. Shank length was significantly and permanently decreased by the -16% and -24% treatments (Table 4-3), which indicates a stunting of the birds mature frame size. Flock Maturation

Feed treatment had a significant effect in delaying the onset of flock maturity (50% production). Mean age and body weight at 50% production for each treatment are presented in Table 4-3. To test the hypothesis that a reduction in body weight will delay flock sexual maturity, the dependent variable body weight (Y, kg) was regressed on the independent variable age (X, days) at 50% production (Figure 4-3). The resulting negative linear regression equation, Y = 5.737 - .0137 (X),
Std. Err. (.426) (.002) Prob. .0001 .0001,













indicates that for every 13.7 g decrease in body weight, within the range of body weights and ages at flock maturity found in this experiment, there was a corresponding delay in flock maturity by 1 day. The resulting negative correlation (r = -.84) was significant and is in agreement with findings by Pearson and Herron (1982b) who also reported a significant negative correlation (r = -.88) between these factors.

Mortality

Mortality was not affected by feed treatment over the life of the flock or when analyzed by pullet or breeder hen phase of growth (Table 4-3). The levels of mortality for all treatments were low compared to levels commonly found in industry. Difficulty in detecting differences among treatments was due to high levels of between-replicate variation. There was a trend, although not significant, for the -24% birds to have higher mortality in the pullet rearing period and lower mortality in the breeder hen laying period. This trend would be in agreement with observations made by Pym and Dillon (1969, 1974) who noted that the net effect of high rearing and low layer mortality would be no difference in overall mortality. Lee et al., (1971) cited numerous reports of lower mortality during the laying period in birds restricted during rearing. From an economic perspective this would be an advantage due to the higher value associated with the breeder hen.













Production Performance

The average hen-day production response to feed

treatment is illustrated in Figure 4-4. Generally, there was a delay in sexual maturity which was proportional to the level of feed restriction. The -16% and -24% feed treatments had a slower rise to peak production, perhaps due to poorer flock uniformity at that time. The production response to all feed treatments peaked at ca. 82 to 84% and the most restricted birds (-24%) remained at higher levels of production from 40 through 65 weeks of age.

Average hen-day production to the common age of 64 wk was significantly lower for the -16% and -24% treatments (Table 4-4). These treatments were in production 8 and 15 days less than STD, respectively. However, at 64 wk of age the -24% treatment was still at 63.4% production which was 11.5% higher than STD and represented the level of production of STD some 10 wk earlier. This implies that production would be likely to continue at acceptable levels to industry for several more weeks. Moreover, there was no significant difference in mean hen-housed production between the -24% and STD treatments to 64 wk of age. Although mortality was not affected by treatment the timing of mortality relative to the production cycle was a contributing factor to there not being differences in hen-


housed production.











76
Hen-day production of double-yolked eggs as affected by feed treatment is illustrated in Figure 4-5. Proportional increases in feed restriction resulted in proportional decreases in hen-day production of double-yolked eggs. The

-24% treatment had significantly lower production of doubleyolked eggs than STD (Table 4-4). Katanbaf et al., (1989b) showed that a standard feed restriction program will produce fewer double-yolked eggs than an ad libitum feeding programs by a difference of 3.5 to 4.0 times. The incidence of double-yolked eggs has been shown to be both strain and season related (Christmas and Harms, 1982).

Hatching eggs per hen housed did not differ

significantly among feeding programs (Table 4-4). The data presented in Table 4-5 compares production cycles by chronological and physiological age. Data based on physiological age was determined by adjusting the first day at 5% production for each replicate to be the start of the production cycle. This adjustment permitted a direct comparison of the production cycles by discounting treatment effects for the delay in sexual maturity (time). Comparison of the -24% and STD production response to feed treatment, adjusted for time, revealed no differences between these treatments.

Egg Characteristics

The effect of the STD and -24% feed treatments on mean egg weight and specific gravity during the production period













is illustrated in Figure 4-6. Generally, the -24% egg weights were proportionately lighter and in parallel with STD as the flock aged. By 58 wk of age egg weights converged and no significant difference in egg weight could be detected (Table 4-6) even though the body weights were significantly different at this time. No differences were found in egg weights pooled over the production cycle. The normally arc-shaped egg weight curve appeared to flatten for all treatments from wk 38 through 52, which corresponded to the period of highest ambient temperatures.

Measurements on specific gravity exhibited similar but reversed trends from egg weight. The -24% treatment had proportionately better shell quality as specific gravity values paralleled STD. No difference between treatments on specific gravity or egg weight measurements could be detected during early or late stages of the production cycle.

The correlation coefficients between egg weight and specific gravity are presented in Table 4-6, with their corresponding probabilities of significance. Correlations within treatments and pooled over the production cycle revealed that all feed treatments had similar and highly significant negative correlations. Correlations among treatments characterize the age effect on these two parameters. The positive correlation at 30 wk of age is due to the delay in the start of the production cycle for the













-24% treatment. At this age, specific gravity values are increasing for the -24%, whereas, the values for STD have already peaked and are decreasing. At the end of the production cycle, egg weights converged and an improvement in specific gravity was found which weakened the negative correlation between these parameters. This could be explained, in part, by the return of cooler ambient temperatures.

Fertility and Hatchability

Data presented in Table 4-7 demonstrate that

quantitative differences in feed restriction, even severe feed restriction, did not have a significant effect on fertility or total hatchability at any age. Moultry (1983) reported lower levels of fertility and hatchability from those birds on severe restriction during rearing and lay. Feed Usage

Cumulative intake of feed, crude protein (CP) and

metabolizable energy (ME) are presented in Table 4-8 on a chronological and physiological basis. Proportional differences in quantities of feed, CP and ME for all treatments were a result of the feed allocation program which was used to maintain parallel growth curves. When measured to the common chronological age of 65 wk the -24% treatment consumed 5.02 kg less feed, .71 kg less protein, and 15.16 Mcal less energy per hen housed for growth, maintenance and production than did the STD. On a



















physiological basis the quantities of feed required for growth and maintenance during the pullet phase was .68 kg less for -24% than STD. Furthermore, the quantity of feed consumed during the production period (breeder hen) was 4.33 kg less for -24% than STD.

The -24% treatment required numerically less feed per

dozen hatching eggs on a hen housed basis than STD (Table 48). This difference was not significant due to levels of between-replicate variation caused by the interaction of feed treatment and environment on the initiation of production. Moultry (1983) reported that the lowest level of feed/dozen eggs resulted from a feeding program that was 10% above standard during rearing then 10% below standard during lay. He found significant and proportional decreases in feed/dozen eggs during the production period as feed was restricted from 10% above to 15% below standard.

In summary, the results of this study indicate that

feed restriction levels below current recommendations can be used with broiler breeder females without significantly affecting fertility, hatchability, mortality or average egg weight. The levels of severe feed restriction used in this study produced a bird with a lighter mature body weight and a smaller frame size. This bird consumed less feed without significantly reducing the number of hatching eggs per hen housed at a common age, when compared to birds fed on a standard feeding program.














TABLE 4-1. Composition, calculated nutrient content and age used for the starter and grower diets

Starter Grower Grower
21% CP 16% CP 12% CP
Ingredient (1-3 wk) (4-8/16-19 wk) (9-15 wk)
%

Yellow corn 65.53 77.43 87.25
Soy (49%) * 31.15 18.84 8.80
Dical Phos 1.23 1.60 1.92
Limestone 1.09 1.13 1.03
Salt .40 .40 .40
Vit-Min** .50 .50 .50
Amprolium .05 .05 .05
BMD40 @50g/ton .05 .05 .05

Calculated Analysis

Protein, % 21.17 16.21 12.17
ME, kcal/kg 2976 3081 3171

Contains 22% Ca and 18.5% P.

Supplied per kg of diet: 6600 IU vitamin A; 220 ICU
vitamin D3; 2.2 mg menadione dimethyl-pyrimidinol; 4.4
mg riboflavin; 13.2 mg pantothenic acid; 39.6 mg
niacin; 499 mg choline chloride; 22 mcg vitamin B12;
125 mg ethoxyquin; 60 mg manganese; 50 mg iron; 6 mg
copper; 0.198 mg cobalt; 1.1 mg iodine; 35 mg zinc.

Calculations based on 3432 and 2460 kcal/kg and 8.8 and
49% CP for corn and SBM, respectively.














TABLE 4-2. Daily nutrient intake of broiler breeders after 20 weeks of age

Nutrient Daily intake / bird

Protein, g 20.6
Sulfur amino acids, mg 754
Methionine, mg 400
Lysine, mg 938
Arginine, mg 1379
Tryptophan, mg 256
Calcium, g 4.07
Phosphorous, mg' 683
Sodium, mg 170
Vitamins2 --Energy3

1Expressed as total phosphorus.

2Levels of vitamins and trace minerals in finished feed met minimum daily intake suggested by National Research Council (1984).

3Diets were formulated for feed intake of 109 to 204 g/bird per day. Examples of energy intake are 301, 398, 495, and 636 kcal per day for diets formulated for 109, 137, 164, and 204 g/bird per day feed consumed.













TABLE 4-3. Effect of feed treatment on growth, development and mortality of breeder hens Feeding program


Variable +8% STD -8% -16% -24%

Growth

20 wk BWT, g 2261 + 26a 2103 + 23b 1935 + 19c 1751 + 23d 1583 + 21e
20 wk CV, % 14.0 13.6 11.9 16.6 15.9

62 wk BWT, g 3765 + 32a 3671 + 38b 3567 + 34C 3425 + 37d 3416 + 29d
62 wk CV, % 9.7 11.6 10.9 12.2 9.7

28 wk SHANK, mm 115.0 + .78 113.7 + .9 114.7 + .8ab 112.5 + .9bc 110.9 + 1.1C 62 wk SHANK, mm 114.3 + .3a 114.2 + .3a 113.2 + .4b 112.1 + .4C 110.9 + .4d Development (Flock maturation)

BWT 50% Prd., g 3157 + 28a 3049 + 36b 2964 + 37b 2809 + 8C 2648 + 42d
Age 50% Prd., d 190 + 1d 197 + ic 205 + 2b 215 i 3a 219 + 2a

Mortality

Life of flock, % 4.6 + 1.5a 5.7 + 1.8a 4.9 + 1.4a 3.8 + 1.3a 4.6 + 1.2a
Pullet phase, % 1.5 + .9a 3.8 + 2.9a 2.3 + 1.5a 1.5 + 1.5a 5.3 + .8"
Breeder phase, % 7.6 + 1.9a 7.8 + 2.0a 7.8 + 2.0a 6.2 + 1.2" 4.0 + 2.4a


BWT= Body weight, CV= Coefficient of variation, SHANK= Shank length.
* F-test ratio of variance (P<.05).
a-b Means within a row having no common superscript are significantly different (P<.05).













TABLE 4-4. Effect of feed treatment on breeder hen mean (� SEM) production performance Feeding program


Variable +8% STD -8%

Hen-day prd
to 64 wk, % 63.5 + .6a 63.1 + .6a 63.3 +

Hen-day prd
at 64 wk, % 54.3 + 1.0c 51.9 + .8c 58.7 +

Hen-housed prd
to 64 wk, % 61.4 + .5a 59.8 + .6a 60.0 +

Hen-housed prd
at 64 wk, % 50.7 + .9cd 48.5 + 1.2d 53.4 +

Hen-day prd
DBL-YLK, % 1.23 + .1a .8 + .ab .7 +

H.E. / H.H.
to 64 wk, no. 176 + 5a 172 + 5a 172 +


a-d Means within a row having no common superscript are H.E./H.H= Hatching eggs per hen-housed.


-16% -24%


.6a 61.0 + .7b 61.0 + .7b


1.1b 59.3 + 1.3b 63.4 + 1.la .6a 57.9 + .7b 59.8 + .7a


.8bc 55.4 + 1.4b 61.7 + 1.4a .1b .5 + .1bc .4 + .1C


3a 166 + 4a 171 + 8a


significantly different (P<.05).











TABLE 4-5. Effect of feed treatment on hen-day production for chronological and physiological ages

Chronological age Physiological age*
Age Week
(wk) +8% STD -8% -16% -24% Prd. +8% STD -8% -16% -24 %


1.7a 11.3a
36.3a 58.5a
72.9a
79.4a 81.8a 84.1 a 83.4a 82.1
81.6a
81.3bc 79.8b 77.0c
76.2b 75.40 72.0d 68.00
63.5d 64.0 c


64 54.3c


Avg.


63.5a


.8b
6.5b
21.9b 42.1b 62.1b 73.1b
81.la 83.5a
82.7a 83.8a 80.4a
82.9b 82.9a 80.7b
77.5b 79.1b 74.6c 67.8c 68.8c 67.9b


51.90


. 3bc 3.10
9.8c 23.5c 38.70
55.5c 66.6b
76.6b 81.5a
82.7a 82.9a 85.6a 83.8a 84.0a 83.0a 79.6b 77.0b 73.9b 72.0b 71.1a

65.3a

58.7b


63.1a 63.3a


1bc 8d
3.8d 10.7d 21.5d 35.3d 45.3c 59.80
71.6b
78.0b 82.6a 82.7b 83.0a
83.3a 82.6a 78.9b 79.6a 72.3b 73. 1ab 71.5a


00 Od
1.0d
4.3e 11.4e
25.3e 40.8d 57.5C
64.9C 71.6c 75.8c 80.00 81. 9ab
84.5a
84.1a 84.6a
81.7a
77.8a 75.7a
74.1a


66.4a 65.8a 59.3b 63.4a 61.0b 61.0a


10.5a
33.9a
58.5a 72.0a
78.6a 81.1a
83.4a 83.4ab 82.4a 81.2a
82.1a 79.4b 77.9b 76.2b 75.3a
72.5a 69.4bc 62.8b 62.9b 62.7b


9.4ab 26.6b 47.0b 67.1a 75.7a
82. la 82.2a 84.4a 83.0a 80.6a 83. la 83.4a 79.4ab 78.4ab 77.5a 73.3a
67.0c 68.7ab 71.0a 67.6a


7.2bc 14.7cd 31.50 49.1"b
65.5b 72.4b 80.la 85.3a 82.8a
82.8a 85.4a 84.9a
83.1la 81.9a
78.1 a 75.8a 70.9abc
73.9a 72.5a 69.8a


5. 5
13 8d 26.3d 38.10 50.6c 64.7c 75.2b 80.2bc 82.3a
83.6a 82.1 a 84. a 80. 3ab 80.5a
76.1la
71.6a 73. 2ab 62.2b
60.3b 67. 1ab


7.0be
18.7C 33.8c 50.1b 63.1b 68.6bc 73.0b 78.6c 81.4a 83.3a
85.5a 84. la 82.8a
80.5 75.9a
74.5a 74.6a 72.3a 71.0a
70.3a


30 62. Ibc 60.80 66.2b 65.9bc 71. la

35 59.2ab 58.5b 61.8ab 60.5ab 63.9a


Avg. 66. la


66.3a 66.5a 64.7b 66.9a


* Determined by adjusting the first day of 5% production for each rep. to be the start of the production cycle.
a-d Means within a row having no common superscript are significantly different (P<.05).












Table 4-6. Effect of feed treatment on mean (+ SEM) specific gravity (SG) and egg weight
(EW), and the correlation between these parameters at various ages

Feeding program


Corr.
Age, +8% STD -8% -16% -24% Pooled Coef.
(wk) /Prob.

30/SG 1.0812 + .0005a 1.0824 + .0004a 1.0820 + .0005a 1.0814 + .0 04a 1.0812 + .bOa 1.0816 + .0002 .262
30/EW 58.2 + .6a 58.2 + .5a 56.6 .7 55.7 .9 55.3 + .2 56.8 + .4 .264
34/SG 1.0812 + .0008b 1.0810 + .O0g4b 1.0832 � .OgO3a 1.0846 + .0 04a 1.0837 + .0004a 1.0827 + .0003 -.691
34/EW 63.4 + .6a 61.4 + .5 60.5 + .6 59.9 + .5 c 58.9 7 .2c 60.8 � .4 .001
38/SG 1.0780 + .0005b 1.0777 + .0004b 1.0786 + 0007b 1.0793 + .0003ba 1.0805 + .0005a 1.0788 + .0003 -.512
38/EW 66.0 + .6a 65.5 + .5ab 64.4 � .2bc 64.7 + .6ab 63.0 � .4c 64.7 � .3 .021
42/SG 1.0741 + .0008b 1.0744 + .0007b 1.0751 + .0004ba 1.0764 + .0002a 1.0766 + .0006a 1.0753 + .0003 -.600
42/EW 65.6 + .6a 65.8 + .8a 64.8 + .6a 65.1 � .6a 64.0 � .2a 65.1 � .3 .005
46/SG 1.0775 + .0007b 1.0773 + .0004b 1.0781 + .0003ba 1.0782 + .0007ba 1.0798 + .0009a 1.0782 + .0003 -.386
46/EW 68.3 + .2a 66.9 + .6ab 66.1 + .5bc 65.4 + .6bc 65.1 T .7c 67.0 � .4 .093
50/SG 1.0747 + .0006b 1.0752 + .0009b 1.0750 + .0006b 1.0782 + .0005a 1.0771 + .0012ba 1.0760 + .0003 -.043
50/EW 67.7 + .7a 67.6 + .9a 66.9 + 1.1a 66.9 + .8a 65.7 � .7a 66.3 ; .3 .856
54/SG 1.0768 + .0004a 1.0760 + .0005a 1.0758 + .0003a 1.0777 + .00 0a 1.0775 + .0005a 1.0767 + .0003 -.181
54/EW 69.4 .4 68.4 .5ab 67.8 .8b 68.3 � 1.0ab 66.8 + .6b 68.1 + .3 .444
58/SG 1.0777 + .0005a 1.0782 + .0006a 1.0783 + .0002a 1.0790 + .0008a 1.0788 + .0010a 1.0784 + .0003 -.263
58/EW 70.3 + .3a 70.2 + .2a 69.1 + 1.0a 69.2 � .8a 69.1 � .4a 69.6 � .3 .263
62/SG 1.0785 + .0008a 1.0786 + .0004a 1.0786 + .0004a 1.0797 + .0008a 1.0798 + .0011a 1.0790 + .0003 -.322
62/EW 72.5 + .3a 71.3 + .6a 71.4 + 1.0a 71.2 + .1a 70.7 � .5a 71.4 T .3 .166

Pooled
/SG 1.0777 + .0004b 1.0779 + .0004b 1.0783 + .0005ab 1.0794 + .0004a 1.0794 + .0004a 1.0785 + 0 -.528
/EW 66.8 + .7a 66.1 + .7a 65.3 + .7a 65.2 + .8a 64.3 : .8a 65.0 : .2 0

Corr.
coef. -.441 -.542 -.593 -.523 -.453
Prob .007 .001 0 .001 .006


a-b Means within a row having no common superscript are significantly different


(P < .05).


Corr. coef.- Pearson's product-moment correlation coefficient and probabilities of significance in parenthesis. 0 L1











Table 4-7.


Effect of feed treatment on mean (� SEM) hatchability of all eggs set (Hatch)


and fertility (Fert) at various ages.
Feeding program

Age, (wk) +8% STD -8% -16% -24% Pooled


32 Hatch
Fert.

36 Hatch
Fert.

40 Hatch
Fert.

46 Hatch
Fert.

52 Hatch
Fert.

56 Hatch
Fert.

62 Hatch
Fert.

64 Hatch
Fert.

Pooled
Hatch Fert.


82.0 +2.9a 91.3 +3.7a

87.0 +2.1a 95.8 +1.3a

86.0 +3.8a 92.0 + 2.1a

85.3 +4.0a 90.0 +3.2a

85.3 +3.6a 91.3 +1.7a

79.3 +3.4a 91.8 +1.3a

83.5 +4. Oa 92.5 +1.9a

75.3 + 1.4a 89.8 +1.8a


82.9 +1.2a 91.8 + .8a


84.0 + 3.1a 94.8 + .6 a

92.0 + 1.5a 95.3 +1.9a

88.3 + 1.8a 95.3 + 1.3a

79.0 +2.7a 81.3 +3.2a

83.0 + 2.6a 90.0 +3.6a

80.0 + 3.5a 93.5 +2.9a

84.0 +3.0a 90.8 +2.7a

75.0 +4.Oa 93.0 +4.4a


83.2 + 1.3a 91.7 + 1.2a


80.8
92.0

86.8 94.5

87.5
95.0

80.3 85.5

82.8 91.3

74.0 87.8

80.8 91.8

78.5 89.8


+2.1a + 2.7a

+ 5.7a +2.9a

+2.7a +2. la

+ 1.3a +2.6a

+2.9a +1.6a

+2.5
+ 2.38

+2.2a + 1.8a

+ 2.5a +3.4a


81.4 +1.2a 90.9 + .9a


82.5
90.5

84.0
91.3

85.0
90.0

83.8
89.5

82.5 89.5

81.8
92.3

85.5 90.0

78.3
91.0


+ 3.3a +3.3a

+2.9a +2.9a

+4.2a +3.9a

+3. 1a +2.4a

+2.la S3 .8a

+ 2.2a + 2. 0a

+3.3a +5.4a

+4.0 a + 4.3


82.9 +.1. 90.5 +1.2a


75.8 + 90.5 +

91.0 +
96.5 +

84.5 + 93.0 +

81.5 +
85.0 +

82.3 + 86.8 +

77.0 + 92.0 +

82.8 + 90.0 +

72.0 + 88.5 +


2. 3a 3.2a

.6a
.7a

3.0a
1.3a

2.6a 3.5a

2.1a 1.8a

2.5a 1. 7

2.0a 2.6a

1.7a 3.6a


81.3 +1.2a 90.3 +1.0a


81.0 +1.2 91.8 +1.2

88.2 +1.4 94.7 + .9

86.3 +1.3 93.1 +1.0

82.0 +1.3 86.3 +1.4

83.2 +1.1 89.8 +1.1

78.4 +1.3 91.5 + .9

83.3 +1.2 91.0 +1.3

75.8 +1.3 90.4 +1.5


82.4 + .5 91.0 + .5


a,b Row means followed by different superscrips differ significantly (P<.05).


-- --














TABLE 4-8. Cumulative feed, crude protein and metabolizable energy various chronological and physiological ages by feed treatment


intake per bird at


Feeding program

+8% STD -8% -16% -24%

Chronological age
20 wk Feed, Kg 8.94 8.32 7.71 7.09 6.49
CP, Kg 1.38 1.29 1.20 1.10 1.01
ME, Mcal 27.70 25.78 23.86 21.95 20.07

35 wk Feed, Kg 25.55 24.03 22.63 20.94 19.28
CP, Kg 3.77 3.54 3.33 3.08 2.83
ME, Mcal 76.63 72.07 67.88 62.81 57.85

65 wk Feed, Kg 57.52 55.93 54.49 52.64 50.91
CP, Kg 8.18 7.94 7.74 7.48 7.23
ME, Mcal 171.71 166.98 162.63 157.01 151.82

Phvsioloqical age
Rearing phase, d 175 179 184 187 194

Pullet Feed, Kg 13.22 12.73 12.58 12.35 12.05
CP, Kg 2.08 2.01 1.99 1.96 1.91
ME, Mcal 39.71 38.20 37.64 36.85 35.90

Breeder Feed, Kg 44.31 43.19 41.91 40.29 38.86
CP, Kg 6.10 5.93 5.75 5.52 5.32
ME, Mcal 132.00 128.78 124.99 120.16 115.92

Life of flock
FEED/DZHE, Kg 3.94 3.92 3.81 3.82 3.59




Full Text
127
from production. The cost of delaying sexual maturity
relates to holding pullets for this additional time.
Enterprise budgets for each feeding program are
presented in Table 6-4, with detailed average component
costs for rearing pullets to 5% production. Comparison of
the budgets revealed that at base prices, the cost of
delaying sexual maturity by ca. 3 weeks was $.170 per pullet
survivor or an average cost that was ca. 3% greater than STD
(1%/wk). Although the delay caused by feed restriction
decreased average PFD cost by $.090, increased PPAY ($.161),
PVAC ($.040), PSRV ($.044) and CHK ($.015) costs totaling
$.261 resulted in the net increase of $.171 per survivor.
The major average cost items in a pullet rearing
enterprise at 5% production were CHK, PFD and PPAY in that
order. PPAY is a function of pullet housing density and
contractual payment rates. Any change in pullet density
will not affect average cost to the integrator, unless
pullet density is increased beyond some tolerance limit and
results in increased mortality.
Figure 6-3 illustrates how sensitive ATC/P was to a 20%
change in a component cost at 20, 25 and 30 wk of age, while
on a STD feeding program. At 20 wk of age ATC/P are more
sensitive, as indicated by the steeper sloping line, to
changes in CHK than PFD costs. However, these costs became
equally important at 25 wk and ATC/P became more sensitive
to PFD at 30 wk of age. ATC/P did not appear to be


53
outliers in the breeder flocks were true outliers and their
inclusion in flock uniformity estimates could confound
interpretations. In the pullet flocks five out of 41
suspected outliers were classified as true outliers. Three
of the five were missexed males and two were either sick or
starve-outs.
Sample size. The average body weight and uniformity
measurements for FXD quantities of breeders and pullets were
not significantly different than PND quantities (Table 3-4).
Figure 3-3 illustrates the effect of a weigh procedure that
prescribes weighing a fixed quantity of birds, i.e., 60
pullets while rejecting suspected outliers (A) on the
frequency distribution of confidence intervals. Compared to
this procedure is a distribution of confidence intervals
that resulted from weighing all pullets in a penned-up
sample (B). The greatest number of suspected outliers in a
pullet flock were, by far, under-weight birds. Therefore,
rejection of these observations would tend to inflate the
mean body weight. Rejection of the extremes of a
distribution, i.e., grossly under- and over-weight birds may
lower the level of sample variance which may therefore
deviate from the true population variance. By weighing all
birds in the penned-up group it should be possible to have
more confidence that the mean estimates the true population
mean.


30
In two separate experiments conducted by Proudfoot et
al. (1984, 1985) lighting programs were initiated at 16, 20,
or 22 wk of age by abruptly increasing the photoperiod from
8 to 12 h and then further increasing the photoperiod
linearly to 14 h by 23 wk of age. There were no significant
overall effects on egg production, body weights or any other
factor except for the number of double-yolked eggs produced
and the longer delay in sexual maturity. Delaying the
implementation of the lighting program also increased egg
size and decreased specific gravity at 29 wk of age. They
recommended photostimulation at 20 wk of age to avoid
problems of lower shell quality resulting from the delayed
program.
Cave (1984a) utilized two lighting programs beginning
at 20 wk of age. Both increased the photoperiod from 6 to
16 h/d by either 5 abrupt increases of 2 h each week or a
gradual 2 h then 1 h, then 14 increases of ,5 h each week.
Mo overall differences due to lighting program in the number
of hatching eggs per hen housed could be detected. Age at
50% production was delayed significantly and egg weight was
lower for the more abrupt lighting program. These
researchers also reported that light intensity had no
significant overall effect on any production trait, despite
a rather strong change from 2 lx to 10 lx at 16, 20, and 22
wk of age. This response was in agreement with findings by
Morris (1967).


16
Proudfoot, F. G., H. W. Huan, and K. B. McRae, 1984.
Effects of photoperiod, light intensity and feed
restriction on the performance of dwarf and normal
maternal poultry meat genotypes. Can. J. Anim. Sci.
64:759-768.
Proudfoot, F. G., H. W. Huan, and K. B. McRae, 1985.
Effects of age at photoperiod change and dietary
protein on performances of four dwarf maternal meat
parent genotypes and their broiler chick progeny. Can.
J. Anim. Sci. 65:113-124.
Proudfoot, F. G., and W. F. Lamoreux, 1973. The bio-
economic effect of nutrient intake restrictions during
the rearing period and post "peak" egg production feed
restriction on four commercial meat-type parental
genotypes. Poultry Sci. 52:1269-1282.
Pym, R. A., and J. F. Dillon, 1969. The effect of some
feeding and laying feeding regimes on the initial
reproductive performance of broiler type pullets.
Proc. Australia Poult. Sci. Conv., 167-178.
Pym, R. A., and J. F. Dillon, 1974. Restricted food intake
and reproductive performance of broiler breeder
pullets. Br. Poult. Sci. 15:245-259.
Rishell, W. A., (NA). Trade-off values affect the genetic
objectives. Arbor Acres Review 23(1):1-4.
Robbins, K. R., S. F. Chin, G. C. McGhee, and K. D.
Roberson, 1988. Effects of ad libitum versus
restricted feeding on body composition and egg
production of broiler breeders. Poultry Sci. 67:1001-
1007.
Romanoff, A. L., and A. J. Romanoff, 1949. The Avian Egg.
John Wiley and Sons, Inc., New York, NY.
Ross Poultry Breeders, Inc., 1986. Ross breeders Broiler
parent stock management manual 208. Elkmont, AL.
SAS Institute Inc., 1985. SAS/STAT guide for personal
computers, version 6 edition. Cary, NC.
SAS Institute Inc., 1987. SAS/Graph guide for personal
computers, version 6 edition. Cary, NC.
Sharp, P. J., G. Beuving, and J. H. Van Middlekoop, 1976.
Plasma lutenizing hormone and ovarian structure in
multiple ovulating hens. Proc. 5th Europ. Poultry
Conf., Malta 11:1259-1264.


113
OVIDUCT
0= +8% STD <§> = -8% -16% 0= -24%
FIGURE 5-7. Effect of feed treatment on oviduct weight (g)
with respect to age (wk) and body weight (g).


CHAPTER II
LITERATURE REVIEW
Introduction
Information in the literature on various broiler
breeder management practices is relatively scarce. Even
more surprising is the paucity of scientific research on
such fundamental issues as weighing programs, bird and flock
behavior, and economic analysis of production. This is
unfortunate because managing today's broiler breeder is a
complex practice that requires knowledge of the bird and the
broad range of factors affecting it.
A review of the current literature reveals that two
basic perspectives have been taken by researchers, one
nutritional, the other physiological. The nutritional
studies have focused on feeding programs and the nutritional
requirements of the bird, whereas the physiological studies
have focused on lighting programs and the physiological
requirements for the initiation of sexual maturity. Both
perspectives are interrelated and are better understood if
examined under a common forum.
It is important to identify from the start a few of the
principal causes of variation and conflicting findings in
10


23
production, with the peak period being long and the
persistency of production acceptable (Costa, 1981). In a
non-uniform flock, small under-developed birds start laying
much later than larger, heavier birds. This results from a
relatively large spread in age at sexual maturity between
early and late layers where individual birds reach maximum
production at very different ages and a high peak is never
achieved.
Petitte et al (1981) reported that increased
uniformity of broiler breeders could be achieved by
segregation according to body weight accompanied by feeding
different protein levels to each weight category. Flock
uniformity measured at 20 wk of age increased from 80 to 89%
by utilizing this management procedure. A more recent study
with non-segregated body weight groupings by Wilson and Dale
(1989) showed that accelerated levels of feed intake (163
g/bird/d) did not improve uniformity when compared to birds
fed at the control level of 150 g/bird/d. Each body weight
group within the flock distribution remained distinct
throughout the study. This suggests that uniformity of
pullet flocks at later ages can only be improved by
segregation and feeding according to body weight groupings.
Housing, systems
Beep litter production systems in combination with
slatted platforms are widely used for broiler breeding stock
to produce fertile hatching eggs by natural mating. One


2
quality and nutrition from the food market place, broiler
meat producers competed actively to fulfill these needs.
Evidence of industry's ability to respond effectively to
this dynamic consumer behavior is the fact that total per
capita consumption of poultry meat increased consistently
over this time period. Also, consumer demand drove further
processed poultry products into all segments of the market
place. Now, over 6,000 specialty products using chicken and
other poultry are marketed by the poultry industry and
further enhancement of this wide product line to meet the
diverse wants of the consumer is expected to continue
(Brown, 1989).
This change to a consumer orientation may seem distant
from the main issue of this dissertation, but it has had a
direct affect on broiler breeder reproductive efficiency and
management practices. Primary breeder companies, those that
market broiler breeder parent stock to the broiler industry,
have shifted their selection emphasis to those phenotypic
traits with the greatest bio-economic importance. For
example, emphasis on selection for increased egg numbers and
hatchability of parent stock lowers growth and feed
efficiency performance in the broiler progeny, conversely,
emphasis on growth rate in the progeny will lower
reproductive performance in the breeder house. The relative
economic importance of parental reproductive traits such as
egg production, hatchability, livability or breeder feed


64
FIGURE 3-1. Effect of early feeding schedule and time of
weighing on broiler breeder female body weight (Exp. 1).
FIGURE 3-2. Cyclic changes in non-laying breeder female body
weight, on an early or late feeding schedule.


SHANK LENGTH
116
FIGURE 5-10. Effect of feed treatment on shank length (mm)
with age (wk).


72
j 1/ 2, ...4; and EiJk = residual effect. When differences
among treatments were obtained, comparisons among means were
made by using the Waller-Duncan K-ratio test and were
considered significant if P < .05 (SAS, 1985). Data on
flock uniformity were analyzed using the general linear
models procedure (SAS, 1985). Differences in flock
uniformity were evaluated by the F-test ratio of variances.
Pearson's product-moment correlations were determined
between hatchability and fertility, and between specific
gravity and egg weight as a measure of linear association
(SAS, 1985).
Results and Discussion
Body Weight and Uniformity
Growth of the STD fed birds throughout the rearing and
breeder periods approximated the growth curve recommended by
Arbor Acres, the primary breeder (Figure 4-2). Growth
curves resulting from all other feed treatments paralleled
STD through 62 wk of age. Some convergence in body weight
during the latter half of the production cycle did occur
especially between the -24% and -16% treatments. As
expected, the effect of feed treatment on mean body weight
at 20 wk of age was significant (Table 4-3) with the -24%
birds being 520 g lighter than STD. Uniformity, as measured
by the coefficient of variation, was significantly better
for the -8% treatment only. A possible trend towards poorer


71
32 to 64 wk using four days production, ca. 100 settable
eggs, from each pen and set according to normal incubation
procedures.
ResearchPeriod and Environment
The relationship of average weekly temperature (highs
and lows), and hours of daylight to the research period is
illustrated in Figure 4-1. Birds were hatched in September,
1987 and commenced production in early March, 1988. The
onset of production coincided with increasing temperatures
and hours of natural daylight.
Experimental Design and Statistical Analysis
The experimental design was a randomized complete block
of five pens replicated 4 times and containing 36 female and
3 male broiler breeders from 28 wk until termination (less
female mortality). The experimental unit was the pen.
Forty-three females were started in each pen with seven
females removed for analysis of physical attributes by 28 wk
of age. The five feed treatments were replicated four times
into blocks that minimized experimental error caused by
temperature or natural daylight gradients within blocks
while maximizing their effects among blocks. Data analysis
utilized a linear statistical model for a randomized
complete block design:
= U + Ti + Bj + Eijk
where U = overall mean; Tt = fixed effect of feed treatment
and i 1, 2, ...5; B.¡ = fixed effect of pen blocking and


LIPID
112
0= +8?: 0= STD cg>= -8* (?= -16% 0= "24%
FIGURE 5-6. Effect of feed treatment on plasma total lipid
(mg/mL) with respect to age (wk) and body weight (g).


91
AGE, £WEEKS}
FIGURE 4-5. Hen-day production of double-yolked eggs (%) as
affected by feed treatment.
AGE, CWEEKS}
FIGURE 4-6. Mean egg weight (g) and specific gravity (g/mL)
plotted over the production period for the STD and -24% feed
treatments.


CHAPTER I
INTRODUCTION
The Joint Council on Food and Agricultural Sciences has
developed national research priorities in the area of animal
production for a number of years. In 1988 the general area
of reproductive efficiency was targeted as a fiscal priority
for research, extension and higher education (Cook, 1988).
Cook noted that this topic was particularly important to the
broiler industry where growth rates and reproduction are
negatively correlated. The Joint Council suggested that
priority be given to research goals which develop
technologies and educational programs that increase the
efficiency and profitability of broiler breeder
reproduction. The goals of this dissertation conform well
with those identified by the Joint Council. Furthermore,
this research endeavor has targeted the broiler breeder
manager as its principal client and attempts to demonstrate
how research findings can be applied to direct field use.
Perhaps the most significant change in the broiler meat
industry over the last ten years was the transition from a
production-driven to a market-driven industry. As American
consumers increased their demand for value, convenience,
1


96
randomized complete block design. When differences among
treatments were obtained, comparisons among means were made
by using the Waller-Duncan K-ratio test (SAS, 1985).
Pearson's product-moment correlations were determined for
all variables as a measure of linear association (SAS,
1985). Three dimensional scatter plots of mean bi-weekly
values of each attribute measured were used to characterize
the AGE X BWT X TREATMENT effect on the onset of sexual
maturity (SAS, 1987).
Results and Discussion
Multidimensional scatter plots illustrating the effect
of feed treatment on various mean physical attributes
associated with the onset of sexual maturity are presented
in Figures 5-1 through 5-8. These plots demonstrate how
each attribute developed over time and in relationship with
body weight. For example, the effect of feed treatment
(Circle= +8%, Diamond= STD, Club= -8%, Heart= -16% and
Spade= -24%) on shank length (Z axis) relative to age (X
axis) and body weight (Y axis) is illustrated in Figure 5-1.
By locating a particular treatment symbol, i.e., spade, at
an early age, i.e., 16 wk, the feed treatment effect on
shank length and body weight is made evident by comparing
the spade (-24%) with the other treatment symbols.
Differences in shank length and body weight resulting from


157
scoring of the head appearance as feedback information when
targeting sexual maturity in a flock. It is recommended
that a quantitative measurement of the comb be made,
recorded and graphed starting at ca. 20 wk of age by the
weighmaster.
Economic Analysis of Feeding Programs
Research findings reported in Chapter IV demonstrated
that the biological response to severe feed restriction
would be an equal number of hatching eggs at 65 wk of age on
a hen housed basis. However, the most severely restricted
birds required less feed to produce this equivalent quantity
of hatching eggs and the most severely restricted birds were
still at a significantly higher rate of production than
standard at 65 wk of age, e.g., ca. 63% vs. 52%.
The overall objective of Chapter VI was to conduct an
economic analysis of this biological response to feed
restriction in order that the economic optimum level of feed
restriction could be determined. Sensitivity analysis was
conducted to illustrate how the average cost of pullet
rearing or hatching egg production was affected by changes
in various fixed and variable costs.
When evaluated at 5% production, reduced feed expenses
due to severe feed restriction were not adequate to offset
the other increased pullet variable costs resulting from
delayed sexual maturity. Therefore, a more expensive pullet


35
by Harms (1984) who utilized data from 49 commercial flocks
to construct body weight curves along with their
corresponding production curves for flocks considered to be
making adequate or inadequate body weight gain. Flocks
categorized as making adequate weight gain peaked at a
significantly higher rate of production and maintained a
rate of 80%, or above, 10 times longer (4.6 vs. .4 wk) than
those with inadequate gain.
The energy restriction research conducted by Pearson
and Herron (1980, 1981) showed that the daily energy intakes
of 440 to 452 Kcal ME/bird/d had higher rates of production
when compared to birds fed 363 Kcal ME/bird/d. Egg weights
did decrease by l to 4 g depending upon the protein level of
the diet. This work was in close agreement with that of
Waldroup and Hazen (1976) who reported that 425 to 450 Kcal
ME/bird/d would maximize egg production. They also
demonstrated that egg weight and body weight were directly
related to caloric intake. Robbins et al. (1988) concluded
that broiler breeder hens reared on a restricted feeding
program and weighing ca. 3400 g at sexual maturity would
require ca. 500 Kcal ME/bird/d for maximum production. This
level of energy intake approximated ad libitum feeding in
this experiment which may not be the case under different
environmental conditions.
These higher energy values differed from findings by
Spratt and Leeson (1987) who reported that 385 Kcal


161
Blair, R., M. M. MacCowan, and W. Bolton, 1976. Effects of
food regulation during the growing and laying stages on
the productivity of broiler breeders. Br. Poult. Sci.
17:215-223.
Blockhuis, H. J., J. W. Van der Haar, and J. M. M. Fuchs,
1988. Do weighing figures represent the flock average?
Poultry-Misset Int. 4(5):17-19.
Bornstein, S., S. Hurwitz, and Y. Lev, 1979. The amino acid
and energy requirements of broiler breeder hens.
Poultry Sci. 58:104-116.
Bornstein, S., and Y. Lev, 1982. The energy requirements of
broiler breeders during the pullet-layer transition
period. Poultry Sci. 61:755-765.
Bornstein, S., I. Plavnik, and Y. Lev, 1984. Body weight
and/or fatness as potential determinants of the onset
of egg production in broiler breeder hens. Br. Poult.
Sci. 25:323-341.
Brake, J., and G. R. Baughman, 1989. Comparison of lighting
regimens during growth on subsequent seasonal
reproductive performance of broiler breeders. Poultry
Sci. 68:79-85.
Brake, J., J. D. Garlich, and E. D. Peebles, 1985. Effect
of protein intake by broiler breeders during the
prebreeder transition period on subsequent reproductive
performance. Poultry Sci. 64:2335-2340.
Brody, T., Y. Eitan, M. Soller, I. Nir, and Z. Nitsan, 1980.
Compensatory growth and sexual maturity in broiler
females reared under severe food restriction from day
of hatching. Br. Poult. Sci. 21:437-446.
Brody, T. B., P. B. Siegel, and J. A. Cherry, 1984. Age,
body weight and body composition requirements for the
onset of sexual maturity of dwarf and normal chickens.
Br. Poult. Sci. 25:245-252.
Brown, R. H., 1989. Poultry industry optimistic as chicken
tops beef. Feedstuffs 61(5):1,39-40.
Bullock, D. W., T. R. Morris, and S. Fox, 1963. Protein and
energy restriction for replacement pullets. Br. Poult.
Sci. 4:227-237.
Cave, N. A., 1984a. Stimulation lighting of meat-type
pullets. Poultry Sci. 63:1101-1104.


48
Figure 3-2 clearly illustrates the cyclic changes in
body weight over a 40 h period when fed on an ERL schedule.
Any change from the initial time of weighing to the follow
up weighing will create an error in the estimated gain. For
example, an initial weighing at 0830 h followed by a
weighing the second day at 0830 h resulted in a 22 g
increase while a weighing at 1030 h will have a potential
error of 7 g by showing a gain of 15 g. If the birds are
weighed on the follow-up day in the afternoon at 1430 h the
estimated change in body weight is a loss of 27 g, or a
difference of 49 g from 0830 to 1430 h. The true gain for
the first 24 h period was 14 g, which was measured from just
prior to feeding (0430 h) on day one, to just prior to
feeding on the second day. This would suggest that weighing
just prior to feeding would be the most effective procedure
in evaluating gain which is in agreement with findings by
Turner et al.. (1983). The drawback to this procedure with
feed restricted birds is the almost frenetic behavior of the
birds at this time that could cause accidental mortality.
Breeder company suggestions to weigh at noon or ca. 3 to 4 h
post-feeding would find the birds at their greatest level of
feed and water intake. Body weights could be rising or
declining at this time, along with the possibility of
significant variation in body weights caused by vomiting.
Furthermore, afternoon hours for weighing should be
discouraged in the summer to avoid stressing the birds


98
effects on shank length; second, maximum shank length was
attained at sexual maturity and plateaued to the end of lay;
third, compensatory growth was not fully attained in the
most severely restricted treatments; and fourth, there
appears to be a ridge line approximated by the -16%
treatment, below which permanent stunting of growth occurs.
Therefore, sexual maturity can also be characterized by
a plateauing of those attributes that serve as important
reserves to reproduction such as, the SHANK (mineral) and
FTPD (energy). Measurements on lean tissue development as a
reserve for protein would have been useful to this analysis,
unfortunately they were not measured. These findings were
consistent with those reported by Katanbaf et al. (1989c)
and Zelenka et al. (1987).
The correlation coefficients and probabilities of
significance for all combinations of attributes at various
ages are presented in Table 5-1. The significance levels of
the correlation coefficients of those attributes that
approximate sexual maturity (LIPID, OVID, and OVARY) with
those physical traits that are potentially measurable by the
breeder manager (ARCH, COMB, and HEAD), demonstrate that
comb measurements and subjective head scores could be used
for feedback information when targeting sexual maturity.
Even though the correlations with ARCH were significant,
measurements of ARCH would be less useful than measurements
of COMB or HEAD because of the gradual linear development of


TABLE OF CONTENTS
Page
ACKNOWLEDGMENTS ii
LIST OF TABLES vi
LIST OF FIGURES ix
ABSTRACT xii
CHAPTERS
I INTRODUCTION 1
Problematic Situation 3
Researchable Problems 4
Hypotheses 5
Experimental Obj ectives 6
Relevance to Farming Systems Research
and Extension 9
II LITERATURE REVIEW 10
Introduction 10
Weighing Programs.... 11
Pullet Rearing Period 20
Pullet-Layer Transition Period 25
Breeder Hen Laying Period 3 3
III TOWARDS AN APPROPRIATE STRATEGY
FOR WEIGHING BROILERS, BROILER BREEDER
PULLETS AND BREEDER HENS 41
Introduction 41
Materials and Methods.... 43
Results and Discussion 47
IV THE EFFECT OF SEVERE FEED RESTRICTION
DURING THE REARING PERIOD ON FEMALE
BROILER BREEDER REPRODUCTIVE PERFORMANCE.... 66
IV


80
TABLE 4-1. Composition, calculated nutrient content and age
used for the starter and grower diets
Starter
Grower
Grower
21% CP
16% CP
12% CP
Ingredient
(1-3 wk)
(4-8/16-19 wk)
(9-15 wk)
%
Yellow corn
65.53
77.43
87.25
soy (49%) #
31.15
18.84
8.80
Dical Phos
1.23
1.60
1.92
Limestone
1.09
1.13
1.03
Salt
.40
.40
.40
Vit-Min**
.50
,50
.50
Amprolium
.05
. .05
.05
BMD40 @50g/ton
.05
.05
.05
Calculated Analysis ***
Protein, %
21.17
16.21
12.17
ME, keal/kg
2976
3081
3171
Contains 22% Ca and 18.5% P.
Supplied per kg of diet: 6600 IU vitamin A: 220 ICU
vitamin D3; 2.2 mg menadione dimethyl-pyrimidinol; 4.4
mg riboflavin; 13.2 mg pantothenic acid; 39.6 mg
niacin; 499 mg choline chloride; 22 meg vitamin B12;
125 mg ethoxyquin; 60 mg manganese; 50 mg iron; 6 mg
copper; 0.198 mg cobalt; 1.1 mg iodine; 35 mg zinc.
Calculations based on 3432 and 2460 keal/kg and 8.8 and
49% CP for corn and SBM, respectively.


136
TABLE 6-2. Base costs, production coefficients and +
adjustments used in sensitivity analysis of a breeder
enterprise
20%
hen
Price
Situations
-20%
BASE
+20%
Averaae Pullet Rearina
Cost / survivor fat 5% Droduction}
a) +8%, $
4.596
5.745
7.894
b) STD, $
4.667
5.834
7.001
c) -8%, $
4.721
5.901
7.081
d) -16%, $
4.766
5.958
7.150
e) -24%, $
4.804
6.005
7.206
Breeder mort., %/wk
. 140
. 175
.210
Breeder feed, $/kg
.100
.125
.150
Producer pay, $/doz.
.24
.30
.36
Adjustment for
Commercial eggs, %/wk
.064
.080
.096
Service &
supervision, $/doz.
.0060
. 0075
. 0090
Hen salvage, $/kg
.229
.286
.343
Egg salvage, $/doz.
.08
.10
.12


159
this information to control the growth and development of
pullets and breeder hens along a body weight curve that is
lower than presently recommended by industry; 3) assuring
that nutritional and lighting needs of the bird during the
pullet-layer transition period are met by recognizing the
onset of sexual maturity of the flock and adjusting the
feeding and lighting programs accordingly; 4) increasing the
housing density of the pullet flocks to a level that
maintains a normal pullet rearing bio-mass (assuming no
change in mortality will occur); and 5) extending the laying
period to ages where average total cost of a dozen hatching
eggs have reached a minimum level (assuming eggshell quality
can be maintained).
The importance of accurate and timely information from
the on-farm weighing program should not be underestimated
and procedures that address this issue should be
institutionalized within the breeder management program
before attempting to use severe feed restriction as a
management technique for optimizing economic returns from
pullet rearing and breeder hen laying programs.


143
FIGURE 6-1. Average cost structure of a standars pullet
rearing program, at base prices.
s

a
s
15 1Q 15 20 25 30
AGE, CWIQ
FIGURE 6-2. Average cumulative feed cost for various pullet
feeding programs.


46
initial weigh time and PM weighings were approximately five
hours after AM weighings.
Pullet farm. Two dark-out houses (Trials 1 and 2)
containing ca. 14,500 replacement pullets were sampled when
8 and 10 wk old on the off-feed day during a skip-a-day
feeding program. Birds were fed at 0700 h and water was
restricted in the afternoon. Each house was equipped with
pan type feeders and nipple drinkers.
Breeder farm. Samples of birds were weighed in two
curtain-sided breeder houses (Trials 1 and 2) containing ca.
7,350 adult breeder hens 36 and 38 wk old and in their tenth
and twelfth week of production. Hen-day production was
about 74% at that time. Females ate from chain feeders and
drank from bell-type waterers, while males ate separately
from pan feeders.
Broiler farm. Body weight measurements were made in
three curtain-sided broiler houses (Trials 1, 2, and 3).
The first was recently built and equipped with nipple
drinkers, pan feeders and contained ca. 24,500 straight-run
broilers 40 d old. The other two were older houses and were
equipped with cup drinkers, pan feeders and each contained
ca. 14,500 straight-run broilers 38 d old.
Statistical Analysis
The TTEST procedure of SAS/STAT (1985) was used to
calculate means for a particular variable under
investigation, and then to test the hypothesis that the


LIST OF FIGURES
Figure Page
3-1 Effect of early feeding schedule and time of
weighing on broiler breeder female body
weight (Exp. 1) 64
3-2 Cyclic changes in non-laying breeder female body
weight, on an early or late feeding schedule 64
3-3 Frequency distribution of confidence intervals
for a fixed quantity of birds excluding outliers
(A) and all birds in a penned-up group (B)....... 65
4-1 Average weekly high (HI) and low (LO)
temperatures and hours of daylight (LIGHT)
during the research period 88
4-2 Live body weight from hatching to 62 weeks of
age as affected by feed treatment 88
4-3 Relationship between body weight (Y, g) and age
(X, d) as affected by feed treatment at 50%
production (flock maturity) 89
4-4 Effect of feed treatment on hen-day
production (%) 90
4-5 Hen-day production of double-yolked eggs (%) as
affected by feed treatment 91
4-6 Mean egg weight (g) and specific gravity (g/mL)
plotted over the production period for the STD
and -24% feed treatments 91
5-1 Effect of feed treatment on shank length (mm)
with respect to age (wk) and body weight (g) 107
5-2 Effect of feed treatment on fat pad weight (g)
with respect to age (wk) and body weight (g) 108
5-3 Effect of feed treatment on pubic spread or arch
(cm) with respect to age (wk) and body
weight 109
ix


62
TABLE 3-7. Classification of suspect outliers as true
outliers by testing mean body weight with an outlier
interval ( 3*SD) for broilers, pullets and breeder hens
(Exper. 3)
Trial
(no.) Age
N
Mean
(g)
3*SD
(g)
Outlier
Interval
(g g)
Suspect
(no.)
Actual
(no.)
Broilers
1
40 d
316
1683
629
(1054,
2312)
4
0
2
38 d
165
1556
566
( 990,
2122)
1
0
3
38 d
166
1615
603
(1012,
2218)
1
0
Breeder hens
1
36 wk
138
3339
776
(2563,
4115)
0
0
2
36 wk
147
3373
896
(2477,
4268)
2
2
1
38 wk
128
3300
998
(2303,
4298)
2
1
2
38 wk
128
3443
980
(2462,
4423)
4
1
Pullets
1
8 wk
218
851
350
( 501,
1202)
7
2
2
8 wk
213
863
390
( 473,
1252)
9
0
1
10 wk
164
1009
434
( 575,
1444)
12
0
2
10 wk
162
1026
471
( 555,
1497)
13
3


BODY WEIGHT,
8!
FIGURE 4-3, Relationship between body weight (Y, g) and age (X, d)
as affected by feed treatment at 50% production (flock; maturity).


79
physiological basis the quantities of feed required for
growth and maintenance during the pullet phase was .68 kg
less for -24% than STD. Furthermore, the quantity of feed
consumed during the production period (breeder hen) was 4.33
kg less for -24% than STD.
The -24% treatment required numerically less feed per
dozen hatching eggs on a hen housed basis than STD (Table 4-
8). This difference was not significant due to levels of
between-replicate variation caused by the interaction of
feed treatment and environment on the initiation of
production. Moultry (1983) reported that the lowest level
of feed/dozen eggs resulted from a feeding program that was
io% above standard during rearing then 10% below standard
during lay. He found significant and proportional decreases
in feed/dozen eggs during the production period as feed was
restricted from 10% above to 15% below standard.
In summary, the results of this study indicate that
feed restriction levels below current recommendations can be
used with broiler breeder females without significantly
affecting fertility, hatchability, mortality or average egg
weight. The levels of severe feed restriction used in this
study produced a bird with a lighter mature body weight and
a smaller frame size. This bird consumed less feed without
significantly reducing the number of hatching eggs per hen
housed at a common age, when compared to birds fed on a
standard feeding program.


125
from the linear pullet mortality function were used to
calculate average total costs (ATC/P) in dollars per pullet
survivor. This analysis projected the average total cost
and its component costs for each feeding program through 30
wk of age. This time frame captured the changes in cost
structure that occurred until birds on all feeding programs
achieved 5% production.
Breeder hen period. Economic evaluation of the breeder
hen period was made from two perspectives. The first
examined average total cost on a breeder hen survivor basis
(ATC/B), so that average cost could be examined
independently of production performance. Secondly, average
total cost was evaluated on the basis of a dozen hatching
eggs produced (ATC/E) which incorporated all aspects of the
production function into the breeder hen cost structure.
Results and Discussion
Pullet Rearing Period
The average cost structure of a standard (STD) pullet
rearing feeding program is illustrated in Figure 6-1.
Pullet average fixed cost (AFC/P) represents the pullet and
cockerel chick cost (CHK) at day of age adjusted for pullet
mortality. Pullet average variable cost for the combined
PPAY, PSRV and PVAC costs (AVC1/P) increased linearly
through 30 wk of age. Whereas, the average pullet variable
cost for feed (AVC2/P) increased linearly to 20 wk and then


45
Experiment 3 (on-farm^
General procedures. A catching pen was used to pen-up
a sample of birds as large as possible without causing
excessive piling. Samples were measured at two locations in
each on-farm house with each house considered a trial. The
first location was along the side wall near a feed dump
(FDD). The second, an end location (END) was along the side
wall at the end door. Birds were weighed individually on a
mechanical SPR scale. Birds in the first pullet house only
were weighed individually on the ELC scale to validate
earlier findings concerning type of scale used.
Weighing procedures were as follows. The weigher
selected and weighed individual birds from the penned-up
sample. A subjective decision was then made to note all
grossly under- or overweight birds as suspected outliers.
This process continued until a predetermined fixed quantity
of bird weights (N=60) was achieved and the last weight
noted. Weighing was then continued until all remaining
penned birds were weighed. All recorded weights were
tabulated under the following treatments: fixed quantity
with suspected outliers included (FXD); fixed quantity with
outliers removed (FXO); and all birds penned including
suspected outliers (PND). Two weeks after the initial
weighing these procedures were repeated in the morning (AM)
for Trial 1 and 2, and afternoon (PM) for Trial 1 only.
Follow-up time of AM weighing was within one hour of the


TABLE 4-4. Effect of feed treatment on breeder hen mean (+ SEM) production performance
Feeding program
Variable
+8%
STD
-8%
-16%
-24%
Hen-day prd
to 64 wk, %
Hen-day prd
at 64 wk, %
Hen-housed prd
to 64 wk, %
Hen-housed prd
at 64 wk, %
Hen-day prd
DBL-YLK, %
H.E. / H.H.
to 64 wk, no.
63.5
+
. 6a
63.1
-6a
63.3
6a
61.0
+
. 7b
61.0
+
. 7b
54.3
+
1.0
51.9
-8
58.7
+ l.lb
59.3
+
1.3b
63.4
+
1.1
61.4
+
. 5a
59.8
6a
60.0
6a
57.9
+
. 7b
59.8
+
. 7a
50.7
+
. 9cd
48.5
1.2d
53.4
+ 8bc
55.4
+
1.4b
61.7
+
1.4
1.23
+
.Ia
.8
.lab
.7
-lb
.5
+
.lbc
.4
+
lc
176 5a
172 + 5a
172 + 3*
166 + 4s
171 + 8s
a'd Means within a row having no common superscript are significantly different (P<.05).
H.E./H.H= Hatching eggs per hen-housed.
03
0J


70
Na, per bird per day (Table 4-2). Adjustments in diet
formulation and allocation were made weekly based on level
of body weight gain and egg production.
Production,Measurements
Egg production and mortality records were kept daily.
Egg production was summarized by phase of maturity, that is,
pullet (1 d to 5% production) or breeder hen (5% production
to 65 wk of age). Average body weight was determined weekly
for each pen by weighing four groups of ca. 8 females and
one group of 3 males through 45 weeks and then bi-weekly
until 62 weeks of age. Average body weight of the STD -
treatment was compared with a target body weight recommended
by Arbor Acres for a particular age, and a feed allocation
made. Feed allocations for all other feed treatments were
quantitatively adjusted from this allocation to STD.
Eggs were collected three times daily, classified as
double-yolked or normal and stored in an egg cooler at 13 C.
Production was recorded daily and summarized by 14 d
periods. Average egg weight was determined weekly by
Individually weighing all normal eggs from one day's
production. Specific gravity was determined once per 4 wk
period, from 30 through 62 wk of age, by weighing eggs
individually then, storing one day's egg production
overnight and the next morning using the saline flotation
method with solutions set at intervals of 0.0025 g/l*
Fertility and hatchability were determined every 4 wk from


TABLE 4-3. Effect of feed treatment on growth, development and mortality of breeder hens
Feeding program
Variable
+8%
STD
-8%
-16%
-24%
Growth
20 wk BWT, g
2261 26a
2103 +
23b
1935 +
19
1751 +
23d
1583 +
21*
20 wk CV, % *
14.0
13.6
11.9
16.6
15.9
62 wk BWT, g
3765 32a
3671 +
Q
CO
n
3567 +
34
3425 +
37d
3416 +
29d
62 wk CV, %
9.7
11.6
10.9
12.2
9.7
28 wk SHANK, mm
115.0 + .7*
113.7 +
. 9ab
114.7 +
. 8ab
112.5 +
. 9bc
110.9 +
1 lc
62 wk SHANK, mm
114.3 + .3
114.2 +
.3*
113.2 +
. 4b
112.1 +
.4
110.9 +
. 4d
Development (Flock maturation^
BWT 50% Prd., g
3157 + 28a
3049 +
36b
2964 +
37b
2809 +
8
2648 +
42d
2*
Age 50% Prd., d
190 + ld
197 +
le
205 +
2b
215 +
3*
219 +
Mortality
Life of flock, %
4.6 + 1.5a
5.7 +
1.8a
4.9 +
1.4a
3.8 +
1.3*
4.6 +
1 oa
Pullet phase, %
1.5 + .9a
3.8 +
2.9a
2.3 +
1.5*
1.5 +
1.5*
5.3 +
L £
.8*
2.4*
Breeder phase, %
7.6 + 1.9a
7.8 +
2.0*
7.8 +
2.0*
6.2 +
1.2*
4.0 +
BWT= Body weight
, CV= Coefficient of variation,
SHANK=
Shank
length.
F-test ratio
of variance (P<
.05) .
05
to


BIO-ECONOMIC ANALYSIS OF SELECTED
BROILER BREEDER MANAGEMENT PRACTICES
BY
THOMAS RICHARD FATTORI
A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
1989

ACKNOWLEDGMENTS
The author wishes to express his most sincere
appreciation to his co-advisors, Dr. Henry R. Wilson and Dr.
Peter E. Hildebrand, for their guidance throughout the
author's Doctor of Philosophy program. Their strong
direction and support of the selected coursework and
research program enabled an understanding of a broad range
of issues important to poultry management.
Special appreciation is extended to other committee
members, Dr. Steve A. Ford, Dr. R. H. Harms, and Dr. F. Ben
Mather, for their encouragement, technical advisement and
guidance throughout the research program.
Additional gratitude is extended to the professors of
the University of Florida Poultry Science Department, Mr.
David P. Eberst, Mr. W. Gary Smith and the farm crew, and
all members of the staff for their assistance in faciliting
the work load over a long research period.
The author is also indebted to Mr. Harold Barnes and
Gold Kist, Inc. for the cooperation and assistance in
conducting research on-farm and whose advice was of great
value.
ii

Sincere appreciation is expressed to the author's
parents, Mr. and Mrs. L. A. Fattori, for their support and
personal encouragement throughout the graduate program.
The author wishes to extend his deepest appreciation to
his wife Maisha for her care and support of their home and
family which freed the many hours needed to complete this
program. Without her patient understanding this endeavor
would have never been completed.
iii

TABLE OF CONTENTS
Page
ACKNOWLEDGMENTS ii
LIST OF TABLES vi
LIST OF FIGURES ix
ABSTRACT xii
CHAPTERS
I INTRODUCTION 1
Problematic Situation 3
Researchable Problems 4
Hypotheses 5
Experimental Obj ectives 6
Relevance to Farming Systems Research
and Extension 9
II LITERATURE REVIEW 10
Introduction 10
Weighing Programs.... 11
Pullet Rearing Period 20
Pullet-Layer Transition Period 25
Breeder Hen Laying Period 3 3
III TOWARDS AN APPROPRIATE STRATEGY
FOR WEIGHING BROILERS, BROILER BREEDER
PULLETS AND BREEDER HENS 41
Introduction 41
Materials and Methods.... 43
Results and Discussion 47
IV THE EFFECT OF SEVERE FEED RESTRICTION
DURING THE REARING PERIOD ON FEMALE
BROILER BREEDER REPRODUCTIVE PERFORMANCE.... 66
IV

Introduction................................ 66
Materials and Methods. 68
Results and Discussion. 72
VCHARACTERIZING THE ONSET OF SEXUAL MATURITY
IN FEED RESTRICTED BROILER BREEDER FEMALES.. 92
Introduction 92
Materials and Methods. 94
Results and Discussion...................... 96
VIECONOMIC ANALYSIS OF SEVERE FEED
RESTRICTION ON BROILER BREEDER PULLET
REARING AND BREEDER HATCHING EGG PRODUCTION. 117
Introduction.117
Materials and Methods 120
Results and Discussion. 125
VIISUMMARY AND CONCLUSIONS. ISO
Weighing Programs........................... 151
Feeding Programs 153
Targeting Sexual Maturity................... 155
Economic Analysis of Feeding Programs....... 157
REFERENCES. 160
BIOGRAPHICAL SKETCH. 171

LIST OF TABLES
Table Page
3-1 Effect of feeding time (ERL vs. LTE) and time
of day on non-laying broiler breeder female
mean body weight and weight change (Exp. 1) 56
3-2 Effect of scale type (ELC vs. SPR) and sample
units (IND vs. GRP), on mean adult breeder hen
and breeder pullet body weight and uniformity
(SD) (Exp. 2) 57
3-3 Effect of sample location (FDD vs. END) and
sample type (PND vs. FXD) on mean straight-run
broiler body weight and uniformity (SD),
(Exp. 3) 58
3-4 Effect of sample location (FDD vs. END) at
various ages and by sample type (PND vs. FXD)
on mean pullet body weight and uniformity (SD),
(Exp. 3) 59
3-5 Effect of sample location (FDD vs. END) at
various ages and by sample type (PND vs FXD) on
mean breeder hen body weight and uniformity (SD),
(Exp. 3) 60
3-6 Effect of sample location (FDD vs. END) on mean
breeder hen and pullet body weight gain (Exp. 3). 61
3-7 Classification of suspect outliers as true
outliers by testing mean body weight with an
outlier interval (+ 3*SD) for broilers, pullets
and breeder hens (Exp. 3) 62
3-8 Effect of sample size on mean and variance of
body weight for broilers, pullets and breeder
hens 63
4-1 Composition, calculated nutrient content and age
used for the starter and grower diets 80
4-2 Daily nutrient intake of broiler breeders after
20 weeks of age 81
vi

4-3 Effect of feed treatment on growth, development
and mortality of breeder hens 82
4-4 Effect of feed treatment on breeder hen mean
( SEM) production performance 83
4-5 Effect of feed treatment on hen-day production
for chronological and physiological ages 84
4-6 Effect of feed treatment on mean (+ SEM)
specific gravity (SG) and egg weight (EW), and
the correlation between these parameters at
various ages 85
\
4-7 Effect of feed treatment on mean ( SEM)
hatchability of all eggs set (Hatch) and
fertility (Fert) at various ages 86
4-8 Cumulative feed, crude protein and metabolizable
energy intake per bird at various chronological
and physiological ages and by feed treatment 87
5-1 Correlation coefficient (r) and the significance
probability that the correlation is zero (P>/r/)
for various physical attributes associated with
sexual maturity 101
5-2 Effect of feed treatment (mean + SEM) on various
physical attributes associated with sexual
maturity 103
5-3 Effect of feed treatment on bursa weight (mean +
SEM) and relative proportion of bursa and fat pad
to body weight 105
5-4 Effect of feed treatment (mean + SEM) on various
physical attributes associated with sexual
maturity 106
6-1 Base costs, production coefficients and +20%
adjustments used in sensitivity analysis of a
pullet rearing enterprise 135
6-2 Base costs, production coefficients and 20%
adjustments used in sensitivity analysis of a
breeder hen laying enterprise 13 6
6-3 Average total cost of a pullet survivor reared
to a common age by feeding program 137
vii

6-4 Effect of feeding program on pullet rearing
average cost budget through 5% production,
calculated at base prices 138
6-5 Effect of feeding program on breeder hen average
cost budget through 40 weeks of production,
calculatd at base prices and expressed as
dollars per survivor 139
6-6 Effect of feeding program on breeder hen average
cost budget through 40 weeks of production,
calculated at base prices and expressed as
dollars per dozen hatching eggs 140
6-7 Average total cost of a dozen hatching eggs
produced to a common age by feeding program,
calculated at base prices and before salvage
adjustments 141
6-8 Live body weight (kg) by feeding program at
various transfer (laying house) ages and the
relative difference (%) among programs 142
viii

LIST OF FIGURES
Figure Page
3-1 Effect of early feeding schedule and time of
weighing on broiler breeder female body
weight (Exp. 1) 64
3-2 Cyclic changes in non-laying breeder female body
weight, on an early or late feeding schedule 64
3-3 Frequency distribution of confidence intervals
for a fixed quantity of birds excluding outliers
(A) and all birds in a penned-up group (B)....... 65
4-1 Average weekly high (HI) and low (LO)
temperatures and hours of daylight (LIGHT)
during the research period 88
4-2 Live body weight from hatching to 62 weeks of
age as affected by feed treatment 88
4-3 Relationship between body weight (Y, g) and age
(X, d) as affected by feed treatment at 50%
production (flock maturity) 89
4-4 Effect of feed treatment on hen-day
production (%) 90
4-5 Hen-day production of double-yolked eggs (%) as
affected by feed treatment 91
4-6 Mean egg weight (g) and specific gravity (g/mL)
plotted over the production period for the STD
and -24% feed treatments 91
5-1 Effect of feed treatment on shank length (mm)
with respect to age (wk) and body weight (g) 107
5-2 Effect of feed treatment on fat pad weight (g)
with respect to age (wk) and body weight (g) 108
5-3 Effect of feed treatment on pubic spread or arch
(cm) with respect to age (wk) and body
weight 109
ix

5-4 Effect of feed treatment on head score (no.,
5=most developed) with respect to age (wk) and
body weight (g) HO
5-5 Effect of feed treatment on comb factor (cm'2)
with respect to age (wk) and body weight (g) m
5-6 Effect of feed treatment on plasma total lipid
(mg/mL) with respect to age (wk) and
body weight (g) 112
5-7 Effect of feed treatment on oviduct weight (g)
with respect to age (wk) and body weight (g)..... 113
5-8 Effect of feed treatment on ovary weight (g)
with respect to age (wk) and body weight (g) 114
5-9 Relationship of mean bursa, weight (g) to body
weight (g) as affected by feed treatment
(TRT A=+8%, B=STD, C=-8%, D=-16%, and E=-24%).... 115
5-10 Effect of feed treatment on shank length (mm)
with age (wk) 116
6-1 Average cost structure of a standard pullet
rearing program, at base prices 143
6-2 Average cumulative feed cost for various
pullet feeding programs 143
6-3 Sensitivity of pullet average total cost to
changes in component costs at 20, 25, and 30
weeks of age for the STD feeding program
(CHK=chick, PFD=pullet feed, PPAY=grower pay,
PMRT=pullet mortality, DENSITY=pullet housing
density) 144
6-4 Sensitivity of pullet average total cost to
changes in component costs at 20, 25, and 30
weeks of age for the -24% feeding program 145
6-5 Effect of a 20% change in component costs on
average total cost per pullet survivor at 5%
production 146
6-6 Average total cost of a dozen hatching eggs for
the STD and -24% feeding programs, with age 146
x

6-7 Sensitivity of breeder hen average total cost
to changes in feed costs (BFD) or costs due to
breeder hen mortality (BMRT) at 40 weeks of
production and for the STD or -24% feeding
programs 147
6-8 Sensitivity of breeder hen average total cost
to changes in pullet depreciation costs (PUL$) or
costs due to breeder hen mortality (BMRT) at 40
weeks of production for the STD and -24%
feeding programs 148
6-9 Effect of changes in pullet housing density on
average total cost per pullet (ATC/P) at 5%
production 149
6-10 Effect of adjusted pullet housing density on
average total cost of a dozen hatching eggs
(ATC/E) on a STD and -24% feeding program, with
age 149
xi

Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy
BIO-ECONOMIC ANALYSIS OF SELECTED
BROILER BREEDER MANAGEMENT PRACTICES
BY
THOMAS RICHARD FATTORI
December, 1989
Chairman: Henry R. Wilson
Cochairman: Peter E. Hildebrand
Major Department: Animal Science (Poultry Science)
Studies were conducted to evaluate bird weighing
procedures and the effect of selected broiler breeder
management practices on pullet and breeder hen growth and
reproductive performance.
Evaluations were made of the effects of sample and
batch size, in-house locations, type of scale, time of
weighing and procedure complexity used in the on-farm
weighing of broiler breeder stock on body weight gain and
uniformity. Time of weighing was shown to be an important
source of error when estimating live weight gain. No
significant differences in average body weight due to scale
type or batch size could be detected. A significant
location effect was found with breeder hens, but not with
broilers or breeder pullets. It was determined that
suspected outliers should not be rejected from the sample.
xii

The effect of quantitative feed restriction on breeder
hen reproductive performance was determined. Proportional
decreases in feed allocation below standard practices
resulted in corresponding decreases in body weight, double-
yolked eggs and number of days in production to 64 weeks.
Egg weight, fertility, hatchability, and female mortality to
64 wk of age were not significantly affected by feed
treatment. A delay in sexual maturity caused a significant
decrease in average hen-day production to 64 wk, but not in
total settable eggs per hen-housed.
The effects of feed restriction on attributes
associated with sexual maturity (comb, bursa, fat pad,
plasma lipid, ovary, oviduct, and shank), were
characterized. The main effect was a delay in the
development of these attributes without significantly
altering their ultimate physiological values, with the
exception of shank length which was permanently reduced by
severe feed restriction.
The economic effect of severe feed restriction on
pullet rearing and breeder hen cost structures was analyzed.
Average pullet rearing cost was increased by ca. 3% when
feed restriction delayed maturity by 3 weeks. The resulting
increased pullet depreciation cost was not offset in the
laying period until ca. 67 wk of age. Projected average
total costs beyond 67 wk were lower for severe restriction
than standard feeding practices, especially if pullet
housing density is adjusted to an equivalent bio-mass.
xiii

CHAPTER I
INTRODUCTION
The Joint Council on Food and Agricultural Sciences has
developed national research priorities in the area of animal
production for a number of years. In 1988 the general area
of reproductive efficiency was targeted as a fiscal priority
for research, extension and higher education (Cook, 1988).
Cook noted that this topic was particularly important to the
broiler industry where growth rates and reproduction are
negatively correlated. The Joint Council suggested that
priority be given to research goals which develop
technologies and educational programs that increase the
efficiency and profitability of broiler breeder
reproduction. The goals of this dissertation conform well
with those identified by the Joint Council. Furthermore,
this research endeavor has targeted the broiler breeder
manager as its principal client and attempts to demonstrate
how research findings can be applied to direct field use.
Perhaps the most significant change in the broiler meat
industry over the last ten years was the transition from a
production-driven to a market-driven industry. As American
consumers increased their demand for value, convenience,
1

2
quality and nutrition from the food market place, broiler
meat producers competed actively to fulfill these needs.
Evidence of industry's ability to respond effectively to
this dynamic consumer behavior is the fact that total per
capita consumption of poultry meat increased consistently
over this time period. Also, consumer demand drove further
processed poultry products into all segments of the market
place. Now, over 6,000 specialty products using chicken and
other poultry are marketed by the poultry industry and
further enhancement of this wide product line to meet the
diverse wants of the consumer is expected to continue
(Brown, 1989).
This change to a consumer orientation may seem distant
from the main issue of this dissertation, but it has had a
direct affect on broiler breeder reproductive efficiency and
management practices. Primary breeder companies, those that
market broiler breeder parent stock to the broiler industry,
have shifted their selection emphasis to those phenotypic
traits with the greatest bio-economic importance. For
example, emphasis on selection for increased egg numbers and
hatchability of parent stock lowers growth and feed
efficiency performance in the broiler progeny, conversely,
emphasis on growth rate in the progeny will lower
reproductive performance in the breeder house. The relative
economic importance of parental reproductive traits such as
egg production, hatchability, livability or breeder feed

3
conversion are not as great as such progeny traits as yield
(with its associated characteristics, including grade and
conformation), feed conversion and growth rate in todays
market environment (Rishell, NA). A percentage change in
processing yield will have a greater effect on profits than
will an equal change in any of the other genetic traits
considered in a breeding program.
Problematic Situation
Different breeding policies among the various primary
breeders result in strains of birds that are suited for
different market conditions. This genetic variability can
be used to an advantage by broiler producers so that a
flexible production response to consumer demand can be
achieved. In fact it is not uncommon for a production
complex to utilize several commercial breeds at the same
time. The problematic situation being that each strain of
bird is best managed by a specific set of procedures.
A successful broiler breeder management program is one
that optimizes the use of feed, labor, capital and other
resources in the production of placeable chicks per hen
housed. The complexity of this challenge is made evident by
the depth and diversity of possible factors that can impact
either negatively or positively on the production process.
Management must account for and control variation in
the growth and development of a particular strain of broiler

breeder caused by differences in the physical and managerial
environments in which they are reared and bred. Those
managers who approach breeder reproductive performance from
a life cycle perspective will find that maintaining the
proper balance between controlled growth and reproduction is
an easier task than those who do not.
Eesearchable Problems.
The primary objective of a broiler breeder management
program is to carefully monitor and control each phase of
growth and development during the life cycle. Breeder
managers are required to constantly make decisions
concerning feed formulation and allocation based on body
weight information generated from a pullet weighing program
or body weight and egg production information in the breeder
hen program. Inaccurate information will result in
inefficient and sometimes costly decisionscostly to the
integrator (increased chick cost), hatching egg producer
(lower payments) and society as a whole (higher meat cost)
as resources are not used efficiently.
The researchable problems identified in this
dissertation relate to this decision making process on the
part of the breeder manager. Specifically, the researchable
problems arise from the breeder managers need to 1)
establish an effective body weight monitoring and control
program, 2) maximize the number of placeable chicks from a

5
breeder rearing and laying program, 3) target sexual
maturity, and 4) optimize economic returns from pullet
rearing and breeder hen laying programs.
Hypotheses
Hyp.oth_e,s,is_l
If procedures for the on-farm weighing of broilers,
broiler breeder pullets and breeder hens can be optimized
with respect to the total time (cost) required to conduct
the weighing program, then monetary returns to the growers,
breeders and integrator will increase. Increased returns
will result from more efficient use of labor and feed
resources, as well as increased breeder reproductive
performance.
Hypqthes is__2
If the appropriate broiler breeder body weight growth
curve resulting from a level of feed restriction can be
identified, then reproductive performance (placeable chicks)
of a housed flock can be maximized.
Hy pot he s i.s_3
If changes in the physical characteristics of a breeder
hen that signal the onset of sexual maturity as she passes
through the pullet-layer transition period can be identified
for various degrees of severe feed restriction, then these

6
traits can be utilized to alert the breeder manager to
ensuing increases in nutritional needs of the flock.
Hypothesis 4
If broiler breeders are severely feed restricted during
the rearing period and the resulting biological response is
an equivalent but delayed reproductive performance relative
to standard practices then, economic returns to the pullet
grower, hatching egg producer and broiler integrator from
restricted feeding will be increased above levels derived
from recommended practices.
Experimental Objectives
Regarding Hypothesis 1
The experimental objectives regarding hypothesis 1 were
to: 1. quantify the cyclic change in body weight over a 48
hour period;
2. illustrate the potential error in estimating weight
gain when weighings are not conducted at the same time each
weighing;
3. determine the effect of scale type, sample units,
sample size, sample location, time of sampling and
complexity of the procedures used in the on-farm weighing of
broilers, broiler breeder pullets and breeder hens, on
average body weight, body weight gain and uniformity;

7
and 4. determine the effect of subjectively removing
suspected outliers from a sample group on average body
weight estimates and uniformity.
Regarding Hypothesis 2
The experimental objectives regarding hypothesis 2 were
to: 1. evaluate the broiler pullet growth response to
various degrees of severe feed restriction;
2. evaluate the breeder hen growth and production
response to various degrees of severe feed restriction;
3. evaluate changes in reproductive physiology related
to severe feed restriction;
4. evaluate the effect of severe feed restriction on
hatching egg characteristics;
and 5. evaluate breeder hen technical efficiencies related
to feed usage and production performance.
Regarding Hypothesis 3
The experimental objectives regarding hypothesis 3 were
to: 1. quantify the effect of severe feed restriction on
various physical attributes associated with sexual maturity
through the pullet-layer transition period;
2. assess the degree of linear correlation among all
quantified physical attributes at various ages;

8
3.characterize in graphic form the age and body-
weight relationships to changes in the various physical
attributes;
and 4. relate findings from the characterization process
to possible field applications.
Regarding Hypothesis 4
The experimental objectives regarding hypothesis 4 were
to: 1. examine the effect of severe feed restriction on
pullet rearing cost structure;
2. determine the cost of delayed sexual maturity due
to various levels of severe feed restriction;
3. test the sensitivity of the average total cost of
rearing a pullet to 5% production to changes in component
costs;
4. examine the effect of severe feed restriction on
breeder hen cost structure;
5. compare breeder hen average total costs on a
survivor and per dozen hatching eggs basis;
6. test the sensitivity of average total cost of
breeder hen hatching egg production to changes in component
costs;
7. estimate the changes in pullet rearing cost
structure due to changes in pullet housing density;
and 8. estimate the changes in breeder hen laying cost
structure to changes in pullet housing density.

9
Relevance to Farming Systems Research and Extension
The strength of the Fanning Systems Research and
Extension (FSR/E) approach to technology generation is
derived, in part, from its systems perspective while
accounting for the biological as well as the socio-economic
factors that impact on the production process. The
vertically integrated broiler production systems of today
are highly complex by agricultural standards and economies
of scale are required in their competitive marketplace. In
such a system, savings of a hundredth of a cent per pound of
product from increased technical efficiencies can translate
into millions of dollars of added net income for growers,
breeders and integrator.
Therefore, FSR/E methodology is perhaps the most
appropriate approach to technology generation at the breeder
level in that it prescribes a complete socio-economic, as
well as biological, analysis of the production system. The
methodology utilized in this research drew upon
multidisciplinary issues that ranged from information
systems to the physiological aspects of sexual maturity. The
result is a dissertation that is more comprehensive than
would have been attained if "traditional" procedures were
followed. Furthermore, client participation in problem
identification and diagnoses was sought out, and diffusion
of research findings back to the client was achieved in a
workshop setting.

CHAPTER II
LITERATURE REVIEW
Introduction
Information in the literature on various broiler
breeder management practices is relatively scarce. Even
more surprising is the paucity of scientific research on
such fundamental issues as weighing programs, bird and flock
behavior, and economic analysis of production. This is
unfortunate because managing today's broiler breeder is a
complex practice that requires knowledge of the bird and the
broad range of factors affecting it.
A review of the current literature reveals that two
basic perspectives have been taken by researchers, one
nutritional, the other physiological. The nutritional
studies have focused on feeding programs and the nutritional
requirements of the bird, whereas the physiological studies
have focused on lighting programs and the physiological
requirements for the initiation of sexual maturity. Both
perspectives are interrelated and are better understood if
examined under a common forum.
It is important to identify from the start a few of the
principal causes of variation and conflicting findings in
10

11
the literature. Environmental effects such as photoperiod,
temperature, humidity, and air and litter quality have a
strong influence on maintenance, growth and production.
Pullet management can interact with breeder management,
especially when birds are moved into new housing for
production. Differences in breeder strain, housing,
equipment, feed ingredients, and feed and water quality can
all be a source of variation in commercial performance as
well as experimental discrepancy or error.
This review will examine the following areas of
interest: weighing programs and pullet rearing, pullet-layer
transition, and breeder hen laying periods.
Weighing Programs
Weighing Methodology
A review of the current broiler breeder management
guides revealed a broad range of recommended sample weighing
techniques. Recommendations ranged from no suggested
methodology at all (Hubbard Farms, 1988-89, and Avian Farms
International, 1989) to extensive procedures by Ross Poultry
Breeders, Inc., (1986). The weighing techniques recommended
by Ross include individually weighing every bird in a
penned-up group (ca. 50 to 100 birds) every week from 4 wk
of age through peak production.
Generally, most primary breeders recommend that birds
be individually weighed weekly, starting at 4 or 5 wk of age

12
and continued through peak production. All birds in a
pernied-up group should be weighed and the weighings should
consistently occur on the off-feed day, at the same time
(afternoon) and at the same locations in the house.
Variation in the number of locations to use in a house range
from 2 to 5 depending upon the company. For example,
Peterson Farms (1988) recommends weighing a minimum of 2% of
the females and 5% of the males each week from 3 wk through
peak production, every two weeks up to 48 wk of age and
monthly thereafter. They suggest group weighing from 3
through 4 wk of age and then individual weighing from 5 wk
on. Sampling should be random and as consistent as
possible. Weigh all birds penned from 4-5 locations in the
house on the off-feed days. Weigh at the same time each
weighing and use the same scale.
The only recent publication found on weighing
methodology was by Harms et al. (1984b), This study was
conducted to develop a method for weighing egg-type pullets
that would be faster, more accurate, and more informative
than previous procedures* They concluded that weighing
replacement pullets in groups of 5 was just as good as
weighing individual birds* The average weight was the same
if all birds penned were weighed. They utilized a 95%
confidence limit to determine whether the birds differed
significantly from a desired target body weight. They also
used the bird-to-bird standard deviation to provide a

13
mathematical value to compare the variation from flock to
flock. The use of sample variance in testing sample
adequacy when weighing broilers was also demonstrated by
Jaap (1955). Jaap recommended weighing ca. 25 birds from 3
locations in a house to estimate the average weight of a
flock of broilers.
gaBESS.g--.of... .Variation
Lilburn et.al. (1987) reported that breeder pullets fed
every day were significantly heavier at each age measured
than those fed every other day, even though mean cumulative
feed intake was not significantly different between
restriction treatments. They noted that part of this extra
body weight in the every~day treatment could be the result
of feed in the crop at the time of weighing. A.more recent
publication (Bennett and heeson, 1989b) comparingskip-a-day
and daily feeding programs, also noted that time of weighing
and feed retention in the digestive tract can strongly
influence the interpretation of growth trials with broiler
breeders.
Meal feeding in broilers was shown to increase
variability of body weights resulting from increased
variability in quantity of crop contents (May et_jyL., 1988,
and Vdrgara et al.. 1989). This finding was shown to be
complicated further by environmental temperatures lower
temperatures increased feed intake and variability in crop
content.

14
Feed restriction influences total water intake as well
as the cyclic patterns of water consumption (Bennett and
Leeson, 1989a). These researchers reported that boredom and
hunger were not the main stimuli of the cyclic pattern of
water consumption associated with feeding programs; they
concluded that the meal on the on-feed day had a much
stronger influence on water consumption than hunger or
boredom on the off-feed day. Quantities of water consumed
can also be affected by diet ingredients. Patterson et al.
(1989) demonstrated that water intake can be increased by as
much as 1.5 times when feeding high fiber ingredients (wheat
middlings) as compared to a lower fiber corn-soy diet. They
also reported that the form of feed can influence water
intake and showed that pelleted feed will increase water
intake over mash. Birds fed high fiber diets tend to eat
more feed to achieve an equivalent intake of energy than
birds on a low fiber diet. This suggests that it is both the
quantity of feed as well as the fiber content that leads to
increased water intake.
Water consumption is also influenced by the strain of
bird used in production (Ogunji et al., 1983). These
researchers reported significant differences in water intake
for two breeder male strains known to exhibit differences in
loose droppings. They also demonstrated that dietary
protein had no significant influence on water consumption.
However, fecal moisture increased as dietary protein

15
increased. Water consumption significantly increased as
dietary salt increased on feed days, but dietary salt did
not influence water consumption on the off-feed days.
Inherent differences in water consumption among strains of
breeders make water, litter and weighing management a
difficult task.
Feed and water management is also influenced by bird
behavior, which in turn can contribute to problems for the
weighing program. Murphy and Preston (1988) found that the
duration of eating and drinking among individuals was
variable.
Appleby et al. (1985) reported on a breeder hen
movement (ranging) study involving commercial flocks of ca.
4000 broiler breeders housed in deep litter. The study was
conducted intensively from 22 to 33 wk of age and then at
monthly intervals until 55 wk of age. They found that
closely restricted ranges did not occur in either sex.
Males had slightly larger ranges than females, but not
significantly so. There was no consistent change in the
area of the house used with age, and nesting was widely
distributed throughout the house. These findings were in
agreement with Craig and Guhl (1969) who reported that
individuals in flocks of chickens do not use space evenly
and that home ranges are either ill-defined or non-existent.

16
llegronle Weighing,Systems
Efficient poultry production requires accurate
information and statistics that enable decision makers to
act in a timely manner. This is especially true for
monitoring and controlling growth and development of almost
every class of poultry. An ideal weighing program would
supply accurate day to day information on growth and
uniformity at a reasonable cost. A variety of electronic
microprocessor-based scales are currently available for
almost every poultry production system and offer the
potential to fulfill these needs.
Lott et al. {1982} and Stutz et al. (1984) described
the development and application of an automated weighing and
analysis system for growth and efficiency studies. They
noted that the prime advantages of such a system were in the
reduction of transcription errors and labor requirements
compared to conventional methods. Feighner et al. (1986)
reported that the implementation of a computerized weighing
system resulted in a 60 to 65% savings in time over manual
acquisition and use of a calculator to analyze the data.
The portability of the micro-computer made it possible to
transport to remote research and production areas.
Meltzer and Landsberg (1988) described the process of
recursive (continual up-dating) calculations and flexibility
of modern data loggers in collecting and analyzing body
weight data. Briefly, a weighing sensor (load cell)

1?
transfers the value of a momentary load of a bird standing
on it into a computer!2ed weight indicator. The hardware
contains a set of adaptive, time-varying filters used to
detect exact weights of a moving, live load. Also, it can
differentiate between, and adjust for, weights caused by
debris left on the platform by establishing previously
defined tolerance limits. The tolerance definitions are
based on the known standard deviations of a normal flock
plus a margin of safety. Each weighing is recorded either
as an in- or out-of-range weight and is placed in its proper
distribution. Pooled in-range weights are subjected to
statistical processing for average and standard deviation
calculations. The calculations are recursive, so that
average and standard deviations are up-dated on each
weighing and all output, including a distribution table and
histogram, are printed on demand.
The reliability of an automatic weighing system is
limited by accuracy of readings and numbers of birds using
the scale. Turner et al. (1983) found there was good
agreement between automatic and manual weighings when a
perch-type platform was used. Their results showed no bias
by the frequent use of the perch by certain individuals to
the exclusion of others. There was, however, an indication
that broilers used the perch less frequently with increasing
age. Newberry et al. (1985) conducted a study with roasters
kept to 10 wk of age to evaluate this effect. Mean body

18
weights obtained on the automatic weighing system were
significantly lower at 7 and 10 wk of age than those
obtained manually. They attributed this result to the
larger birds at later ages perching with part of their
weight in contact with the floor and recommended raising the
perch higher with age. Birds observed on the weighing perch
on one day of the week were 3.5 times more likely to use the
perch again on the following two days. Perching rate
decreased from 41.6 birds/h in wk 1 to 4.3 birds/h in wk 10.
Blockhuis et al. (1988) reported that in broiler trials
comparing manual to automatic weighing systems, the
automatic (platform scale) gave a consistently lower value
than weighing by hand. The difference becoming greater as
the birds aged from 4 to 6 wk. A study on the behavioral
response to the electronic scales made with both male and
female broilers, showed that the percentage of the tagged
birds that made use of the scales and the average frequency
of use of the scale differed significantly with age and sex.
The average frequency of use of the scale was higher for
females especially at 6 wk of age. This would explain the
lower average weights generated by the automatic weighing
system. A possible explanation for this behavior would be
the relatively lower activity of the heavier males. Between
flocks there was considerable variability in the behavior of
the flocks towards the weighing system. Those flocks that
demonstrated higher male activity had average weights from

19
the electronic scale closer to the manual estimates for body
weight and uniformity.
A recent study on filial and sexual imprinting in
precocial birds (Lavie, 1988) showed that broiler chicks
raised on a commercial farm can be attached to and follow an
imprinting stimuli during the rearing period. Chicks were
subjected to a 3 wk imprinting process from day of age. The
stimulus was comprised of plastic boxes containing a music
cassette that was turned on for 10 minutes every 40 minutes
through 3 wk of age in the brood area of a house. After 3
wk the boxes were placed over the full length of the house
drawing imprinted birds to their new location. Relocation
for the imprinted birds was significantly better than
controls. This report confirmed results of an earlier study
by Gvaryahu et al. (198?) who demonstrated that meat strain
chicks can be attracted to an imprinting stimulus, and the
imprinting object could then be used to move birds from a
training area to a new location. More recently Gvaryahu et,
al. (1989) reported that filial imprinting results in
reduced stress behavior and improvements in growth
performance in male chicks. The implication here is the
potential use of imprinting behavior on the automatic
weighing systems. Blockhuis et al. (1988) began their study
at 4 wk of age with no attempt at familiarizing the birds
with the new scales

20
£ullet_.,.Rearipg, Period
Mortality
Lee et al. (1971) cited 63 experiments out of 80 where
higher mortality was associated with feed restriction during
the rearing period, and most of the increase was due to
coccidiosis. since restricted birds are known to increase
litter intake (Harms etal., 1984a) and water intake
(Patterson, 1989) it is not surprising that levels of
mortality due to coccidiosis would be higher* However, Pym
and Dillon (1974) noted that when coccidiosis is well
managed, restriction levels of 60 to 80% of ad libitum
appeared not to have a detrimental effect on rearing
mortality. These researchers also showed that heat stress
mortality for birds fed ad libitum was significantly higher
than for restricted fed birds. They observed that during
the heat stress period the more severely restricted birds
moved around more freely and drank much more water than
birds fed ad libitum.
Mortality levels for pullets reared on 12, 14, 16 and
18% protein diets were not significantly different for
broiler breeders (summers et al., 1967). This was in
contrast to findings by Bullock et al. (1963) and Blair,
(1972) who found increased mortality among pullets fed even
lower protein (10%) grower diets.

21
Behavior
Although feed restriction programs are currently
considered essential to ensure acceptable levels of
livability, fertility and hatchability, feed restriction
itself can cause marked behavioral and physiological changes
in growing birds. These effects can have a negative impact
on flock performance. Mench and Shea (1988) found that male
broiler chicks placed on a skip-a-day feeding program were
more aggressive than males fed ad libitum. This display of
aggression manifested more on the off-feed days than on the
feed days. Competition for food is generally considered a
strong stimulus for aggressive behavior. Aggressive
behavior (pecking activity) was shown to be age related with
peak aggression displayed between 9 and 10 wk of age. The
intensity of aggressive behavior shifted from higher levels
on off-feed days to higher levels on feed days by 24 wk of
age.
Van Krey and Weaver (1988) showed that broiler breeder
pullets provided only 45% of the recommended feeder space
responded in terms of growth and uniformity as well as, or
better than, those given 90% of the recommended feeder
space. They noted that all semblance of social order
disappears during the period of frenetic feeding immediately
after food is made available. As a result, all birds are
able to consume at least some feed despite very limited
feeder space.

22
Studies undertaken to compare the growth and uniformity
of birds reared under skip-a-day and daily feeding programs
(Bennett and Leeson, 1989b) showed that body composition and
flock uniformity were unaffected by feeding program. Daily
feeding increased body weight gain indicating that feed is
more efficiently utilized under this feeding program. Those
researchers as well as Lilburn (1986) noted more aggressive
feeding behavior when birds were fed daily.
Comparison trials evaluating a skip-a-day with a skip-
two-days feeding program (Bartov et al.. 1988) found that
body weights of birds on the skip-two-days program were
significantly less, but maintained significantly better
levels of uniformity than birds fed on a skip-a-day program.
The decrease in body weight was also associated with a
significant delay in the onset of production, however, no
differences in production to 35 wk of age was detected.
Uniformity:
The importance of flock uniformity is underscored in
nearly every broiler breeder management guide and poultry
production book available to producers, uniformity is
usually measured as the percent of the birds that weigh
within + 10% of the average flock weight (North, 1984).
Acceptable uniformity is when 80% of the birds are in that
weight range. Relatively poor uniformity can result in a
production cycle that is characterized as having a slow
increase to peak production, never reaching a high peak

23
production, with the peak period being long and the
persistency of production acceptable (Costa, 1981). In a
non-uniform flock, small under-developed birds start laying
much later than larger, heavier birds. This results from a
relatively large spread in age at sexual maturity between
early and late layers where individual birds reach maximum
production at very different ages and a high peak is never
achieved.
Petitte et al (1981) reported that increased
uniformity of broiler breeders could be achieved by
segregation according to body weight accompanied by feeding
different protein levels to each weight category. Flock
uniformity measured at 20 wk of age increased from 80 to 89%
by utilizing this management procedure. A more recent study
with non-segregated body weight groupings by Wilson and Dale
(1989) showed that accelerated levels of feed intake (163
g/bird/d) did not improve uniformity when compared to birds
fed at the control level of 150 g/bird/d. Each body weight
group within the flock distribution remained distinct
throughout the study. This suggests that uniformity of
pullet flocks at later ages can only be improved by
segregation and feeding according to body weight groupings.
Housing, systems
Beep litter production systems in combination with
slatted platforms are widely used for broiler breeding stock
to produce fertile hatching eggs by natural mating. One

24
alternative to this system for breeders is the use of cages,
which necessitates the labor-intensive practice of
artificial insemination. If breeder females are to be kept
in cages, appropriate feeding and body weight control
programs need to be developed. McDaniel (1974) showed that
broiler breeder hens generally produce more eggs when kept
in cages. However, Fuquay and Renden (1980) reported that
hens maintained in floor pens produced more eggs per day
than hens kept in cages. In their experiment caged females
had significantly higher body weights and significantly
greater variation (less uniformity) in body weights than
floor-reared females. Caged birds generally exhibited
equivalent fertility and hatchability through 59 wk of age,
although they also had higher levels of mortality than floor
birds.
Petitte et al. (1982) reported that caged breeder hens
had significantly heavier body weight and egg weight as
compared to floor birds. Neither mortality nor cumulative
production showed any difference between housing method?
however, during the peak production period the caged hens
exhibited significantly higher levels of production.
A follow-up study by Petitte et al. (1983) showed that
the fertility of the artificially inseminated caged breeders
was significantly lower than that of the naturally mated
birds. Hatchability of eggs at 26 wk was not affected by
housing method? however, hatchability of eggs set at 36 and

25
54 weeks of age was significantly lower for caged than floor
housed hens.
Iggs from caged hens hatched significantly heavier
chicks than the floor housed counterparts which was
attributed to the difference in egg weight observed through
the laying period (Petitte et al., 1982). Measurements on
specific gravity were not reported in this study. Harms
ai* (1984a) found that specific gravity of eggs from hens
with access to litter was higher than hens housed on wire
floors, without a significant difference in egg weight.
They attributed this finding to increased intake of fecal
phosphorous, calcium and other nutrients important to egg
shell formation. Also, they reported that a decrease in
dietary calcium resulted in increased litter consumption.
It appears that caged broiler breeder hens produce larger
eggs with poorer shell quality that result in a concomitant
decrease in hatchability.
Pullet-haver Transition. Period
Bornstein and Lev (1982) discussed their view of the
changing nutritional needs of the bird through the pullet-
layer transition period in terms of flock dynamics. They
concluded, until nearly all the birds in a flock have
started to lay, average flock weights depend more on the
relative proportion within the flock of immature pullets,
prelaying pullets, and laying hens than on the weights of

26
the laying hens. Therefore, any feeding program designed to
promote early egg production also enhances early average
body weights, without necessarily affecting the actual
weights of the laying hens. These researchers found that
earlier maturity and higher egg production were associated
with higher energy intake during the prelay period. The
effect of increased energy during this period on egg weight
was dependent on the age at which the increase in energy was
provided.
McDaniel (1983) showed that quantitative differences in
feed allocation during the prelay period significantly
affected shell quality and egg weight throughout production.
Increased feed allocation, i.e., 176 g/bird/d, from 17
through 20 wk of age stimulated an earlier onset of
production when compared to a more gradual increase in feed
allocation.
Protein
Research conducted by Cave (1984b) showed that protein
levels (15.4 vs. 18.1%) during the prelay period had no
effect on age at 50% production, egg weight, incidence of
cracked eggs, hatchability or mortality. However, the 18.1%
protein treatment showed higher levels of egg production
through 50 wk of age. One possible explanation of this
finding relates to the important changes in the development
of the reproductive system at this time (Yu and Marquardt,
1974). Cave (1984b) suggested that perhaps the higher

27
protein levels improved liver metabolism and function and/or
strengthened the infundibulum which could aid in the
capturing of ovulated yolks. This suggests that as the bird
passes through the pullet-layer transition period a
quantitative change in protein required for the development
of the reproductive tract is separate from the need for body
weight gain (Li1burn, 1987).
Energy
A study conducted by Brake et al. (1985), investigating
protein, energy and their interactions revealed that
significant protein X energy interactions occurred for egg
weight during wk 25 through 44, but not overall. Wo
differences in the main effect of protein level on egg
specific gravity or fertility were found.
Ingram and Wilson (1987) reported that hens fed ad
libitum for various lengths of time during the pullet-layer
transition period laid at higher rates than their more
restricted counterparts through ca. 43 wk of age. However,
after wk 44 the hens full fed for 6 to 8 wk laid at a
significantly lower rate than the more restricted birds.
This was perhaps due to excessive levels of body weight gain
past 40 wk which led to body weights in excess of 4.0 Kg by
this time.
Robbins et al. (1988) reported that ad libitum feeding
during the pullet-layer transition resulted in more eggs,
but the effect was not significant. Egg weight and specific

28
gravity were significantly affected by hen age and not feed
treatment.
Lighting Programs
An important management tool that must be considered
along with a planned feeding program is an appropriate
lighting program. A well managed lighting program is a cost
effective way to regulate the onset of sexual maturity. The
objective being the synchronization of sexual maturity,
through feeding and lighting programs, with management
production and scheduling needs. The normal procedure is to
increase the length of the daily photoperiod from an
inhibitory 6 to 12 h/d to a stimulatory photoperiod of 12 to
17 h/d, starting at point-of-lay (Morris, 1967).
Recommendations for light stimulation of breeder
pullets should be strain specific according to Cave (1984a).
He found significant differences in the production response
to abrupt vs. gradual increases in light stimulation for two
different strains of meat-type birds. This finding was
contrary to conclusions drawn by Proudfoot et al (1980) who
reported no important genotype X photoperiod treatment
interaction when evaluating various abrupt and gradual
lighting programs. However, Proudfoot et al. (1984)
concluded that dwarf genotypes also require a different
light management program than normal strains for optimum
reproductive performance.

29
Payne (1975) reported that an abrupt increase in
photoperiod from 6 to 16 h/d had a significant effect in
advancing the onset of sexual maturity when compared to a
gradual 1 h/wk increase from 6 to 16 h/d. However, this
procedure produced more smaller eggs than the gradual
increase in photoperiod. He also found that pullets reared
on a 6 h photoperiod then gradually increased to 16 h by 34
wk of age had improved reproductive performance and weighed
significantly less, both at the beginning and end of the
laying period when compared with pullets reared using a
constant 15 h photoperiod.
Whitehead et al. (1987) also compared abrupt vs.
gradual lighting programs. The gradual program started at
18 wk of age and increased .5 h/wk to a maximum 18 h at 38
wk of age. The abrupt program began at 19 wk with a rapid
increase of l h/wk to 26 wk then a gradual .5 h/wk increase
to a maximum 17 h at 30 wk of age. The different lighting
programs had no significant effect on any aspect of
reproduction performance in dwarf broiler breeders.
Ingram et al. (1988) demonstrated that initiation of a
stimulatory lighting program at 20 wk was superior to one
initiated at 16 wk of age. Light treatments were ca.
13L:11D increased by 15 or 30 minutes to 15L:9D at 24 wk.
In this experiment, lighting program had a greater effect on
the more restricted (lighter body weight) group.

30
In two separate experiments conducted by Proudfoot et
al. (1984, 1985) lighting programs were initiated at 16, 20,
or 22 wk of age by abruptly increasing the photoperiod from
8 to 12 h and then further increasing the photoperiod
linearly to 14 h by 23 wk of age. There were no significant
overall effects on egg production, body weights or any other
factor except for the number of double-yolked eggs produced
and the longer delay in sexual maturity. Delaying the
implementation of the lighting program also increased egg
size and decreased specific gravity at 29 wk of age. They
recommended photostimulation at 20 wk of age to avoid
problems of lower shell quality resulting from the delayed
program.
Cave (1984a) utilized two lighting programs beginning
at 20 wk of age. Both increased the photoperiod from 6 to
16 h/d by either 5 abrupt increases of 2 h each week or a
gradual 2 h then 1 h, then 14 increases of ,5 h each week.
Mo overall differences due to lighting program in the number
of hatching eggs per hen housed could be detected. Age at
50% production was delayed significantly and egg weight was
lower for the more abrupt lighting program. These
researchers also reported that light intensity had no
significant overall effect on any production trait, despite
a rather strong change from 2 lx to 10 lx at 16, 20, and 22
wk of age. This response was in agreement with findings by
Morris (1967).

31
The effectiveness of a lighting program is complicated
by the feeding program and by seasonal differences in
natural photoperiod and light intensity, out-of-season
flocks, i.e., those hatched January to May, experience
delayed sexual maturity and poorer reproductive performance.
Brake and Baughman (1989) studied the effect of light source
and intensity during rearing for both in- and out-of-season
flocks. They found that light intensity during the rearing
period may need to be somewhat lower than that of the laying
period in broiler breeders which are exposed to fall
(decreasing natural daylight) conditions during the early
phase of lay. These findings were consistent with data
presented by Morris (196?) suggesting that supplemental
light is most beneficial during fall and winter months of
lay.
Sexual Maturity
It is well known that restricting feed intake of
broiler breeder females during the rearing period will
retard growth and delay the onset of sexual maturity (Lee gt
al., 1971? Pym and Dillon, 1974; Watson, 1975; Leeson and
Summers, 1982). When changed from restricted feeding to
either an accelerated or ad libitum feeding program, various
degrees of compensatory growth can occur depending upon the
degree of restriction through the rearing period and the age
at the change. Brody et al. (1980) showed that after severe
feed restriction which delayed the onset of sexual maturity

32
well beyond a normal age, birds did not fully compensate in
growth. Instead body weights remained about 25% lighter
than mature body weights of the control group, When the
severely restricted birds were changed to an ad libitum
feeding program, sexual maturity ensued in a uniform manner.
This study concluded that a minimum body weight and
chronological age were required for the onset of sexual
maturity.
In 1984 five papers on the subject of sexual maturity
appeared, four utilizing broiler breeders and one using
Japanese Quail. Seller et al. (1984b) demonstrated that
body fat content or fat percentage alone is not sufficient
to initiate sexual maturity. More importantly they
concluded that there is a minimum lean body mass requirement
for the onset of sexual maturity in poultry. This finding
was also reported by Zelenka et al. (1984) and Oruwari and
Brody, (1988) with Japanese quail,
Bornstein et al. (1984) confirmed findings of a minimum
requirement for fat and lean tissue stores in conjunction
with chronological age and demonstrated that these
thresholds are strain specific. These researchers, as well
as Pearson and Herron (1982a), reported a significant
negative correlation between age and body weight at first
egg.
Comparisons made by Brody et al. (1984) between normal
and dwarf strains of broiler breeders illustrated the extent

33
to which differences in body weight and age at sexual
maturity can be affected by genetic variation. Age at first
egg ranged from 153 to 173 d in normal breeders and 167 to
173 d in dwarf breeders. The greatest difference between
pullets at sexual maturity and their nonlaying controls were
in the size of the abdominal fat pad and the reproductive
organs. This result suggests that increases in fat prior to
sexual maturity, instead of being general to the carcass,
are restricted to a few organs related to the partitioning
of energy for reproductive performance.
Breeder Hen Laving Period
Because mature broiler breeders are capable of
consuming feed far in excess of their energy requirement for
maintenance and egg production it is economically
advantageous to formulate broiler breeder hen diets on a
daily nutrient intake basis (Wilson and Harms, 1984).
Pearson and Herron (1981) noted that broiler breeder hens
are sensitive to energy intake during the breeding period.
Extra dietary energy enabled birds to gain more weight (fat)
and this had a depressing effect on egg production,
fertility and hatchability (Pearson and Herron, 1982a;
Spratt and Leeson, 1987a). Furthermore, as the rate of lay
decreases, more energy is available for fat deposition so
the initial negative effects on production are likely to be
maintained or increased through lay.

The degree of sensitivity to energy intake is also
dependent on the season of the year. Chaney and Fuller
(1975) and Luther et al. {1976} reported that egg production
and egg size are reduced more severely by a decrease in
energy intake during the winter than during the summer,
since the energy requirement for maintenance of body
temperature is higher in the winter there are fewer calories
that remain for egg production. These authors suggested
that obesity per se does not reduce egg production since fat
birds can lay at a normal rate, but the obese birds suffer
from excessive mortality which results in depressed levels
of hen-housed production. In addition, McDaniel et al.
(1981a) and Pearson and Herron (1981) demonstrated that
over-consumption of energy by broiler breeder hens adversely
affected hen-day egg production, fertility, hatchability and
specific gravity.
Energy
A successful feeding program based on energy
restriction demands an easily applied and practical
guideline. Bornstein et al. (1979) suggested that the use
of average daily weight gain as an indicator of the degree
of energy restriction would be appropriate. Likewise,
Pearson and Herron (1980, 1981) recommended that body weight
control during egg production be considered as a criterion
for assessing the adequacy of energy intake. The
consequence of this recommendation was clearly illustrated

35
by Harms (1984) who utilized data from 49 commercial flocks
to construct body weight curves along with their
corresponding production curves for flocks considered to be
making adequate or inadequate body weight gain. Flocks
categorized as making adequate weight gain peaked at a
significantly higher rate of production and maintained a
rate of 80%, or above, 10 times longer (4.6 vs. .4 wk) than
those with inadequate gain.
The energy restriction research conducted by Pearson
and Herron (1980, 1981) showed that the daily energy intakes
of 440 to 452 Kcal ME/bird/d had higher rates of production
when compared to birds fed 363 Kcal ME/bird/d. Egg weights
did decrease by l to 4 g depending upon the protein level of
the diet. This work was in close agreement with that of
Waldroup and Hazen (1976) who reported that 425 to 450 Kcal
ME/bird/d would maximize egg production. They also
demonstrated that egg weight and body weight were directly
related to caloric intake. Robbins et al. (1988) concluded
that broiler breeder hens reared on a restricted feeding
program and weighing ca. 3400 g at sexual maturity would
require ca. 500 Kcal ME/bird/d for maximum production. This
level of energy intake approximated ad libitum feeding in
this experiment which may not be the case under different
environmental conditions.
These higher energy values differed from findings by
Spratt and Leeson (1987) who reported that 385 Kcal

36
ME/bird/d and 19 g of protein were sufficient to maintain
normal reproductive performance of individually caged
broiler breeder females through peak egg production. At 36
wk of age they noted an unexplainable accelerated decline in
egg production along with a drop or no gain in body weight
between 32 and 36 wk of age. This suggests that inadequate
feed allocations were made at this stage and perhaps the
ideal level of energy intake should be higher than the
reported 385 Keal ME/bird/d.
Research conducted by Leeson and Summers (1982)
demonstrated that excessive energy intake resulted in early
maturity and reduced numbers of settable eggs. Early
maturing birds gained more weight post peak than the control
group even though the feed allowance was identical. This
implies that over-fed birds divert feed energy to body mass
rather than egg production. Peak egg production was 10%
lower than standard and egg size was significantly smaller.
Because obese birds have a higher maintenance requirement
than lighter birds when they mature, initial egg size is
smaller and often not suitable for incubation.
Protein
Waldroup et al. (1976) found that the protein
requirement over the entire production period of broiler
breeders raised on litter and fed a corn-soy diet without
supplemental amino acids was approximately 20 to 22 g/d.
Wilson and Harms (1984) revised their original

37
recommendations for protein and sulfur amino acid
requirements (Harms and Wilson, 1980) by suggesting that
nutrient specifications for broiler breeders include daily
intakes of 20.6 g protein, 754 mg sulfur amino acids, 400 mg
methionine, 938 mg lysine, 1379 mg arginine, 256 mg
tryptophan, 4.07 g calcium, 683 mg total phosphorous, and
170 mg sodium. Pearson and Herron (1981) recommended 19.5
g/d crude protein when reared on litter and when amino acid
intake was balanced. Caged breeder hens were shown by
Pearson and Herron (1982b) to require 16.5 g/d protein .
The absolute energy requirement associated with optimum
production will depend upon the actual maintenance energy
requirement which is likely to differ between cage and floor
systems as well as between strains (Pearson and Herron,
1982b).
Double-Yolked Eggs
The phenomenon of multiple ovulations (double-yolked
eggs) in the chicken has been reviewed by Romanoff and
Romanoff (1949). Zelenka et al. (1986) noted there appears
to be two major categories of multiple ovulations,
sequential and simultaneous. Sequential multiple ovulations
result in extra-calcified compressed-sided eggs, whereas,
simultaneous multiple ovulations result in eggs with more
than one yolk. Conrad and Warren (1940) reported three ways
that double-yolked eggs might occur. First, 65% resulted
from the simultaneous development and ovulation of two ova.

38
Second, 25% resulted from two ova, which were developing a
day apart, being ovulated simultaneously. Third, the
remaining 10% resulted from successive development and
release of two ova, one remained in the body cavity for a
day and was then picked up by the oviduct along with the
newly released ovum. Zelenka et al. (1986) suggested that
the main cause of double-yolked eggs is that two ova reach
maturity and are released at the same time. They also
reported on the unusual situation where two ova can develop
and be released from a single ovarian follicle. They
suggested that this may have resulted from two separate and
distinct oocytes being encapsulated together by granulosa
layer cells during the intitial stages of follicular
development, or incomplete separation of oocytes following
meiotic cytokinesis.
Dobbs and Lowry (1976) utilized dietary dyes to
demonstrate that, in most cases, both yolks were ovulated
within 2 to 3 h of each other. Lowry et al. (1979) reported
that 80% of the pairs developed at the same time and that
ovulation sites were found to occur at random on the surface
of the ovary.
Hormonal mechanisms that control the development of the
ovarian follicular hierarchy were reported by Sharp et al.
(1976) who concluded that multiple ovulation in a super
ovulatory line of chickens was not due to a defect in the
luteinizing hormone releasing mechanism but to an abnormal

39
development of ovarian follicles. The inheritance of the
tendancy to produce double-yolked eggs through genetic
selection has been demonstrated by Lowry and Abplanalp
(1967), Abplanalp and Lowry (1975), and Abplanalp et al.
(1977). Williams and Sharp (1978) reported that as laying
breeder hens become older, the initial decrease in egg
production and the increase in egg size is a reflection of
the way in which yellow yolk accumulates in a smaller number
of follicles which grow to a larger size before they
ovulate. Furthermore, the incidence of double yolked eggs
is normally reduced to low levels as the breeder hen ages.
Christmas and Harms (1982) summarized data on 12
strains of egg-type hens to determine the influence of
strain and season of the year on the incidence of double-
yolked eggs in the initial stages of lay. They found a
significant strain effect on the incidence of double-yolked
eggs at the onset of lay. The incidence ranged from 1.1 to
3.5% hen-day production. Spring and summer-housed laying
hens produced a greater number of double-yolked eggs than
did those housed in the late fall or winter months. The
incidence of double-yolked eggs and age at 50% production
were significantly correlated, however, it was thought to be
a season rather than a within-strain maturity effect.
Feed restriction during the rearing period has been
shown to limit the production of yellow follicles and the
incidence of double ovulations, leading to an increase in

40
the number of settable eggs during this period (Fuller et
al. 1969; Chaney and Fuller, 1975? Zelenka et al.. 1986;
Hocking et al., 1987, 1989? and Katanbaf et al.. 1989b).
Hocking et al. (1989) reported that feed restriction which
resulted in the reduction of the number of yellow follicles
at sexual maturity was associated with lighter, leaner birds
with lower maintenance requirements, but delayed sexual
maturity. Heavier birds were associated with higher numbers
of follicles, whereas, fatter birds were associated with
fewer numbers of follicles. This suggests that a positive
relationship exists between ovulation rate and lean tissue
mass. These authors recommend that feed restriction should
be continued to point of lay.

CHAPTER III
TOWARDS AN APPROPRIATE STRATEGY FOR WEIGHING
BROILERS, BROILER BREEDER PULLETS AND
BREEDER HENS ON-FARM
Introduction
The ability to estimate average body weight and flock
uniformity accurately is an important part of breeder and
broiler managers/ duties. Average body weight estimates of
commercial flocks are used constantly to evaluate breeder
growth and development relative to a particular strain's
standard. Decisions concerning the proper feed allocation
required to consistently achieve a target body weight
objective over a period of time are based on these estimates
and any error in their accuracy will be reflected in the
inefficient growth and production of the flock. Also,
decreases in flock uniformity, i.e., increased variation in
body weight, is a sign of suboptimum husbandry conditions,
the cause of which must be identified and corrected in a
timely manner or production inefficiencies will persist or
worsen.
An appropriate weighing program is an important process
that assures the maintenance of technical and economic
efficiencies in the pullet and breeder houses as well as the
41

42
processing plant. A weighing program is considered
appropriate for a particular attribute (mean body weight and
flock uniformity) in a particular field condition
(restricted or full fed) if it satisfies several conditions.
First, the accuracy of the estimated attribute must be as
good as, or better than, a level required to achieve an
objective. The objective in this case is to determine the
best nutrient allocation or other management decision
necessary to achieve body weight and uniformity standards.
Secondly, the cost of conducting a weighing program must be
within the practical limits of resources available.
A review of the various management guides published by
the breeder companies confirms the lack of consensus
concerning suggested weighing procedures. Recommendations
range from weighing 1, 2, or 3% of the flock to sampling 2,
3, or 4 locations in a house. Furthermore, none of the
management guides quantify for the breeder manager what
level of technical or economic inefficiency will result if
the procedures are not followed.
There has been little or no research conducted on
weighing procedures that maintain a practical level of
accuracy of the weigh data while minimizing the cost of
collecting those data.
The objective of this study was to establish general
guidelines for the development and implementation of an
appropriate weighing program. Specifically, the objectives

43
of Experiment 1 were to quantify the cyclic nature of body
weight gain in a 48 h period and to demonstrate the degree
of error in estimating gain when weighing programs are not
scheduled at a consistent time interval. The objectives of
Experiment 2 (on-station) and 3 (on-farm) were to determine
the effect of scale type, sample units (individual vs.
group), sample size, sample location, time of sampling, and
complexity of procedures used in the on-farm weighing of
broilers, broiler breeder pullets and breeder hens on
average body weight gain and uniformity.
Materials and Methods
Experiment 1
Trials 1 and 2. Eight pens containing 16 Arbor Acres
broiler breeder females, 25 wk old and not yet in
production, were divided into two feeding programs. The
first, an early feeding time (ERL) allocated 122 g of
feed/bird/d at 0430 h and the second, a late feeding time
(LTE) allocated an equivalent amount of feed at 1530 h.
Each feeding program consisted of two groups of two pens
each with a significant difference in average body weight
between groups. These weight class groupings (trials) could
then simulate different houses or farms and the effect of
initial body weight evaluated. Each pen was weighed, eight
birds per crate (two crates per pen), at 2 h intervals
starting at 0430 h and ending at 2030 h on the first day,

44
with the same procedure repeated the following day. Crated
birds were weighed on an electronic scale (Detecto, model
EF-218-56) with a gross capacity of 90.7 kg (200 lb) and a
precision of 45 g (0.1 lb). The four crate weights for each
trial were pooled and the average body weight and change
(gain or loss) for each time period calculated.
Experiment 2
Trials 1. 2 and 3. Three weight class groupings,
totaling 274 Arbor Acres broiler breeder females, 41 wk old
and near peak production, were used to test the accuracy of
different types of scales (electronic vs. mechanical) and
sample units (individual vs. group) in determining average
body weight and uniformity. Three groupings (trials) were
used to simulate body weight conditions found on different
farms. Each trial consisted of six pens containing ca. 15
adult breeder hens. Birds were crated seven or eight birds
to a crate depending upon the population size within a pen.
The weigh routine was as follows: crate weights (GRP)
were measured on an electronic Detecto scale to the nearest
45 g; birds were individually (IND) removed from the crate
and weighed, first on an electronic (ELC) scale (Weltech,
model BW-1) to the nearest 1.0 g and then on a mechanical
(SPR) spring scale (Salter, model 235) to the nearest 45 g.
All weighings were conducted by the same person and data
recorded by a technician to expedite the flow of procedures.

45
Experiment 3 (on-farm^
General procedures. A catching pen was used to pen-up
a sample of birds as large as possible without causing
excessive piling. Samples were measured at two locations in
each on-farm house with each house considered a trial. The
first location was along the side wall near a feed dump
(FDD). The second, an end location (END) was along the side
wall at the end door. Birds were weighed individually on a
mechanical SPR scale. Birds in the first pullet house only
were weighed individually on the ELC scale to validate
earlier findings concerning type of scale used.
Weighing procedures were as follows. The weigher
selected and weighed individual birds from the penned-up
sample. A subjective decision was then made to note all
grossly under- or overweight birds as suspected outliers.
This process continued until a predetermined fixed quantity
of bird weights (N=60) was achieved and the last weight
noted. Weighing was then continued until all remaining
penned birds were weighed. All recorded weights were
tabulated under the following treatments: fixed quantity
with suspected outliers included (FXD); fixed quantity with
outliers removed (FXO); and all birds penned including
suspected outliers (PND). Two weeks after the initial
weighing these procedures were repeated in the morning (AM)
for Trial 1 and 2, and afternoon (PM) for Trial 1 only.
Follow-up time of AM weighing was within one hour of the

46
initial weigh time and PM weighings were approximately five
hours after AM weighings.
Pullet farm. Two dark-out houses (Trials 1 and 2)
containing ca. 14,500 replacement pullets were sampled when
8 and 10 wk old on the off-feed day during a skip-a-day
feeding program. Birds were fed at 0700 h and water was
restricted in the afternoon. Each house was equipped with
pan type feeders and nipple drinkers.
Breeder farm. Samples of birds were weighed in two
curtain-sided breeder houses (Trials 1 and 2) containing ca.
7,350 adult breeder hens 36 and 38 wk old and in their tenth
and twelfth week of production. Hen-day production was
about 74% at that time. Females ate from chain feeders and
drank from bell-type waterers, while males ate separately
from pan feeders.
Broiler farm. Body weight measurements were made in
three curtain-sided broiler houses (Trials 1, 2, and 3).
The first was recently built and equipped with nipple
drinkers, pan feeders and contained ca. 24,500 straight-run
broilers 40 d old. The other two were older houses and were
equipped with cup drinkers, pan feeders and each contained
ca. 14,500 straight-run broilers 38 d old.
Statistical Analysis
The TTEST procedure of SAS/STAT (1985) was used to
calculate means for a particular variable under
investigation, and then to test the hypothesis that the

47
means of two groups of observations were equal. The F-test
ratio of sample variance (Montgomery, 1984) was used to test
the hypothesis that the variance of two groups of
observations were equal. Differences between groups of
observations were considered significant if P < .05.
Results and Discussion
Experiment 1
Time of weighing. Initial body weights prior to
feeding on the first day were 2582 and 2676 g for Trial 1
and, 2747 and 2727 g for Trial 2 (Table 3-1). Change in
body weight (gain or loss) data from the pooled trials
(Table 3-1) demonstrate (Figure 3-1) how birds on the LTE
program reached a 205 g peak change in body weight in 3 h
after feeding, which was greater than the 155 g peak change
in the ERL program which also occurred at 4 h after feeding.
Birds on the LTE program lost weight, starting from peak
body weight and ending just prior to feeding, at the rate of
8.6 g/h while the rate for the ERL program was slower at 7.1
g/h. These differences in feeding programs suggest that
birds on a LTE program may require greater quantities of
water. The higher level of gain due to possible increased
water intake could explain the greater mass lost over this
time period. This finding also suggests that water
restriction should not begin for at least 4 h after birds
have finished eating.

48
Figure 3-2 clearly illustrates the cyclic changes in
body weight over a 40 h period when fed on an ERL schedule.
Any change from the initial time of weighing to the follow
up weighing will create an error in the estimated gain. For
example, an initial weighing at 0830 h followed by a
weighing the second day at 0830 h resulted in a 22 g
increase while a weighing at 1030 h will have a potential
error of 7 g by showing a gain of 15 g. If the birds are
weighed on the follow-up day in the afternoon at 1430 h the
estimated change in body weight is a loss of 27 g, or a
difference of 49 g from 0830 to 1430 h. The true gain for
the first 24 h period was 14 g, which was measured from just
prior to feeding (0430 h) on day one, to just prior to
feeding on the second day. This would suggest that weighing
just prior to feeding would be the most effective procedure
in evaluating gain which is in agreement with findings by
Turner et al.. (1983). The drawback to this procedure with
feed restricted birds is the almost frenetic behavior of the
birds at this time that could cause accidental mortality.
Breeder company suggestions to weigh at noon or ca. 3 to 4 h
post-feeding would find the birds at their greatest level of
feed and water intake. Body weights could be rising or
declining at this time, along with the possibility of
significant variation in body weights caused by vomiting.
Furthermore, afternoon hours for weighing should be
discouraged in the summer to avoid stressing the birds

49
during the hours of highest temperatures. An ERL feeding
schedule coupled with an evening weigh program is one
logical alternative; birds have settled down, voided most
feed, water and eggs, and temperatures are cooler. In this
scenario, variation in body weights as well as undue stress
could be minimized at no additional cost to the program.
Experiment 2
Scale type. Average body weight estimates measured on
the SPR scale were numerically higher but not significantly
different from measurements made on the ELC scale (Table 3-
2). The on-farm validation of these findings was upheld in
Experiment 3. An observation noted during these experiments
was that the automatic printing feature of the ELC scale
decreases the possibility of a transcription error and the
time (cost) necessary for weighing.
Sample unit. All trials conducted on-station
demonstrated that the average body weight determined by
individually weighing birds was not significantly different
than group weighing with crates of seven or eight birds
(Table 3-2). However, the estimates of flock uniformity as
measured by the standard deviation (SD) among observations
was significantly greater and more representative of the
true flock uniformity, when birds were weighed individually.

50
Experiment 3 (on-farm^
Location Effect
^.'fo-'^^-dhtrun broilers. Body weight and body weight
uniformity estimates for the FDD and END house locations are
presented in Table 3-3. In general, broiler weights and
flock uniformity were not found to be different between
locations. There was a significant difference in average
body weight in Trial 3, which was attributed to the chance
occurrence of a slightly higher ratio of males sampled at
the FDD location at that particular sampling.
Pullets. Average body weight was not found to be
different between locations in either trial or at the ages
tested (Table 3-4). This observation would tend to be
consistent with findings of Van Krey and Weaver (1988) in
which it was shown that all semblance of social order
disappears during the period of frenetic feeding.
Significant differences in uniformity were found at the two
locations in trial one at 8 and 10 wk of age. The greater
variation at the FDD location was attributed to including
suspect outliers in the sample. Removal of these
observations on the basis of their being true outliers, as
shown in Table 3-7, resulted in levels of uniformity at both
locations that were no longer significantly different.
Breeders hens. A statistical difference in average
body weight of breeder hens due to house location was found
in Trial 1 at 36 and 38 wk of age without there being a

51
difference in uniformity (Table 3-5). However, the END
location was greater at 36 wk while the FDD was greater at
38 wk. Furthermore, the 38 wk, PM weighing failed to detect
differences in location suggesting that the END location
actually gained weight during the day by feeding and
drinking later. Perry et al. (1971) noted that after
laying, a period of feeding and drinking followed, which
suggests earlier laying by the END location. Trial 2 does
not substantiate these findings. No significant differences
in average body weight or uniformity between locations were
detected for any PND sample. It is difficult to determine
from these data if the differences found in Trial 1 at the
various ages were due to changing flock dynamics or sampling
error. Consistency in the uniformity data as well as the
low number of detected outliers suggests that there could be
significant behavioral differences at various locations in
the house. Appleby et al. (1984) found considerable
movement of both males and females throughout the house.
However, their study was conducted in buildings 46 m long,
whereas these data were collected in buildings 122 m in
length.
Time of weighing. The importance of consistently
weighing at the same time each scheduled weighing
(Experiment 1) is underscored with breeder pullets and
laying breeder hens. Two principal observations can be made
from the data presented on both AM and PM weighings in

52
Tables 3-4 and 3-5, which are evaluated and presented in
Table 3-6. First, the measurement of average body weight
gain of the pullets decreased by ca. 10 g/h between the AM
and PM weighings, despite the fact they were off feed. This
was determined from Table 3-6 where the difference in pullet
body weight from AM to PM at 10 wk (Trial 1) ranged from a
loss of 43 g to 67 g over the 4 h period. Secondly, average
body weight gain data for the adult breeder hens were not as
conclusive. Birds in the FDD location gained weight over
the two week period in both Trial 1 (66 and 77 g) and Trial
2 (141 and 142 g), however they lost weight (-8 and -35 g)
between the AM and PM weighings in Trial 1. This was in
marked contrast to birds weighed at the END location which
lost considerable weight (-141 and -159 g) over the two week
period but gained back nearly 25-30% of it (36 and 60 g)
between the AM and PM trials. The principal conclusion
being that flock dynamics in the breeder house contribute to
a complex situation where relatively radical changes in body
weight occur throughout the day. This is especially true
during the morning hours when feeding, drinking and laying
are all contributing to variation in body weights.
Outliers. Information required to determine if a
grossly under- or overweight bird should be rejected as a
true outlier to the normal body weight distribution is
presented in Table 3-7. No true outliers were detected in
the straight run broiler flocks. Half of the suspected

53
outliers in the breeder flocks were true outliers and their
inclusion in flock uniformity estimates could confound
interpretations. In the pullet flocks five out of 41
suspected outliers were classified as true outliers. Three
of the five were missexed males and two were either sick or
starve-outs.
Sample size. The average body weight and uniformity
measurements for FXD quantities of breeders and pullets were
not significantly different than PND quantities (Table 3-4).
Figure 3-3 illustrates the effect of a weigh procedure that
prescribes weighing a fixed quantity of birds, i.e., 60
pullets while rejecting suspected outliers (A) on the
frequency distribution of confidence intervals. Compared to
this procedure is a distribution of confidence intervals
that resulted from weighing all pullets in a penned-up
sample (B). The greatest number of suspected outliers in a
pullet flock were, by far, under-weight birds. Therefore,
rejection of these observations would tend to inflate the
mean body weight. Rejection of the extremes of a
distribution, i.e., grossly under- and over-weight birds may
lower the level of sample variance which may therefore
deviate from the true population variance. By weighing all
birds in the penned-up group it should be possible to have
more confidence that the mean estimates the true population
mean.

54
Sample size relative to flock size was determined by
sequentially adding 10 pullets or 20 breeders to their
respective samples, while evaluating the change in variance
as measured by the standard deviations, Table 3-8. A
stabilized level of sample variance would indicate that the
sample size achieved a level where additional observations
would not change the estimate of the population variance.
The sample variance peaked with a sample size slightly under
one percent of the population for the straight-run broilers
and pullets tested in these trials. Estimated sample
variance in a breeder flock peaked at only 0.5% of the
population. These levels of peaked variance would define an
absolute minimum sample size that could be used to estimate
flock body weight and uniformity.
It is known that the statistical accuracy of a sample
estimate generally increases with the sample size as a
percent of the flock size, number of sampling locations
selected per house, and the complexity of the sampling
procedures used. However, an increase in the sample size,
and/or number of locations will increase the cost of
weighing and disrupts the flock. Therefore, the choice of
an appropriate method of weighing broilers, broiler breeder
pullets, and breeder hens is primarily concerned with
maintaining the proper balance between the sample size and
number of locations that achieve a minimum cost without

55
sacrificing an adequate level of accuracy for the decision
making process.
In summary, this study demonstrated that the required
balance between accuracy and efficiency of an appropriate
weighing program could be maintained if average body weight
and flock uniformity estimates were derived from one
convenient location, weighing all birds in a penned-up
sample, a number of penned-up samples with a total bird
count approximating at least one percent of the flock size,
and weighings conducted at the same time each weigh period.
Those elements of a comprehensive weighing program that
have the greatest impact on the level of accuracy of the
estimate, but do not add appreciably to the total cost of
data collection, e.g., time of weighing, should certainly be
given the greatest consideration.

TABLE 3-1. Effect of feeding time (ERL vs. LTE) and time of day on non-laying broiler
breeder female mean body weight and weight change (Exp. 1)
ERLa
LTEa
Trial 1
Trial 2
Pooled
Trial 1
Trial 2
POOLED
Day
Time
(h)
BWT
(g)
Change
(g)
BWT
(g)
Change
(g)
BWT
(g)
Change
(g)
BWT
(g)
Change
(g)
BWT
(g)
Change
(g)
BWT
(g)
Change
(g)
1
04:00
04:30
2582
FEED
NA
2747
FEED
NA
2664
FEED
NA
2785
NA
2818
NA
2801
NA
06:30
2723
140
2864
118
2794
129
2774
NA
2806
NA
2790
NA
08:30
2755
173
2884
138
2820
155
2754
NA
2792
NA
2773
NA
10:30
2737
155
2883
136
2810
145
2724
NA
2774
NA
2749
NA
12:30
2725
143
2872
125
2798
134
2708
NA
2754
NA
2731
NA
14:30
15:30
2701
119
2842
95
2772
107
2676
FEED
NA
2727c
FEED
NA
2701
FEED
NA
16:30
2670
88
2816
70
274
79
2839
182
2889
176
2864
179
18:30
2670
88
2806
60
2738
74
2870
213
2910
197
2890
205
20:30
2647
65
2795
48
2721
57
2859
202
2896
183
2877
192
2
04:00
04:30
2601
FEED
19
2755
FEED
9
2678
FEED
14
2794
118
2822
95
2808
106
06:30
2747
165
2896
150
2821
157
2785
110
2815
88
2800
99
08:30
2769
188
2916
170
2842
179
2767
91
2813
86
2790
89
10:30
2772
191
2899
153
2835
172
2745
70
2802
75
2774
72
12:30
2750
168
2881
135
2816
152
2720
44
2779
52
2750
48
14:30
15:30
2727
145
2859
113
2793
129
2694
FEED
19
2757
FEED
30
2725
FEED
24
16:30
2700
118
2835
89
2767
104
2779
104
2832
105
2806
104
18:30
2679
97
2818
72
2748
84
2874
199
2910
183
2892
191
20:30
2663
81
2806
60
2735
71
2879
203
2900
173
2889
188
aERL= Early feed time (0430h); LTE= Late feed time (1530 h); NA=Not applicable.
bTrial 1 and 2, average of two pens.
Initial body weight prior to feeding.
ui

TABLE 3-2. Effect of scale type (ELC vs. SPR) and sample
unit (IND vs.GRP), on mean adult breeder hen and breeder
pullet body weight and uniformity (SD), (Exp. 2)
57
Age Trial Scale type Sample unit
(wk)
No
#
ELC
SPR
Sig.
IND
GRP
Sig.
38
1
N no.
90
90
90
12
mean, g
4029
4063
NS1
4029
4074
NS
SD, g
399
399
NS2
399
196
*
38
2
N no.
90
90
90
12
mean, g
3781
3811
NS
3881
3874
NS
SD, g
336
331
NS
336
152
*
38
3
N no.
94
94
94
12
mean, g
3597
3624
NS
3597
3644
NS
SD, g
319
322
NS
319
125
*
40
1
N no.
90
90
90
12
mean, g
4036
4063
NS
4036
4053
NS
SD, g
415
419
NS
415
191
*
40
2
N no.
89
89
90
12
mean, g
3816
3842
NS
3816
3797
NS
SD, g
361
360
NS
361
237
*
40
3
N no.
94
94
94
12
mean, g
3635
3663
NS
3635
3632
NS
SD, g
320
325
NS
320
289
*
8
4
N no.
111
111
mean, g
844
855
NS


SD, g
130
133
NS

8
5
N no.
107
107
mean, g
862
847
NS


SD, g
101
97
NS
1 t-test on sample means (P<.05).
2 F-test ratio on sample variance (P<.05).
ELC= Electronic scale SD= Standard deviation
SPR= Spring scale Sig= Significance (P<.05)
IND= Individually weighed
GRP= Group weighed

58
TABLE 3-3. Effect of sample location (FDD vs. END) and
sample type (PND vs. FXD) on mean straight-run broiler body
weight and uniformity (SD),(Exp. 3)
Age Trial Pop. Sample Location
(d)
No.
Size
Type
FDD
END
Sig.
Pooled
40
1
24,500
PND
N,
no.
70
78
mean, g
1683
1663
NS1
SD,
9
198
199
NS2
PND
N ,
no.
81
87
mean, g
1674
1708
NS
SD,
g
206
232
NS
All
N ,
no.
151
165
316
mean, g
1678
1687
NS
1683
SD,
g
202
217
NS
210
FXD
N ,
no.
50
mean, g
1670

SD,
g
211

38
2
14,500
PND
N ,
no.
100
65
165
mean, g
1562
1551
NS
1558
SD,
g
199
173
NS
189
FXD
N ,
no.
50

mean, g
1623

SD,
g
228
___
38
3
14,500
PND
N ,
no.
80
86
166
mean, g
1665
1564
*
1613
SD,
g
194
196
NS
201
FXD
N ,
no.
50

mean, g
1566

SD,
g
212

xt-test on sample means (P<.05).
2F-test ratio on sample variance (P<.05).
FDD= Feed dump location SD= Standard deviation
END= End location Sig= Significance (P<.05)
PND= All birds penned
FXD= Fixed quantity

59
TABLE 3-4. Effect of sample location (FDD vs. END) at
various ages and by sample type (PND vs. FXD) on mean pullet
body weight and uniformity (SD) (Exp. 3)
Trial 1
Trial 2
Age
Location
Location
(wk)
Time
Type
FDD
END
Sig.
FDD
END
Sig.
8
AM
PND
N no.
111
107
113
100
mean, g
855
847
NS
854
873
NS
SD, g
133
97
*
129
131
NS
FXD
N no.
60
60
60
60
mean, g
890
862
NS
866
884
NS
SD, g
142
97
*
131
133
NS
10
AM
PND
N no.
92
72
mean, g
991
1033
NS
1022
1033
NS
SD, g
146
140
NS
156
159
NS
FXD
N no.
60
60
60
60
mean, g 1031
1050
NS
1032
1027
NS
SD, g
138
134
NS
167
163
NS
10
PM
PND
N no.
88
96
___
mean, g
948
974
NS


SD, g
168
145
*

'
FXD
N no.
60
60


mean, g
974
984
NS


SD, g
162
143
NS

1 t-test on sample means (P<.05)
2 F-test ratio on sample variance (P<.05).
FDD= Feed dump location SD= Standard deviation
END= End location Sig= Significance (P<.05)
PND= All birds penned
FXD= Fixed quantity

TABLE 3-5. Effect of sample location (FDD vs. END) at
various ages and by sample type (PHD vs. FXD) on mean
breeder hen body weight and uniformity (SD), (Exp. 3).
Sample
TRIAL 1
~>} *
TRIAL
2
Age/Time
type
FDD
END
Sig.
FDD
END
Sig.
36 wk/AM
PND
1 no.
69
69
77
70
mean, g
3291
3387
**
3342
3388
NS
SD, g
241
268
NS2
310
326
NS
FXD
N no.
60
60
60
60
mean, g
3296
3385
*
3337
3412
NS
SD, g
252
261
NS
295
330
NS
38 wk\AM
PND
N no.
64
64
64
64
-
mean, g
3356
3245
*
3482
3403
NS
SD, g
356
300
NS
326
292
NS
FXD
n no.
60
60
60
60
mean, g
3373
3240
NS
3478
3395
*
SD, g
356
300
NS
362
298
NS
38 wk\PM
PND
N no.
62
62
mean, g
3348
3281
ms
X-
sd, g
320
268
NS
FXD
N no.
60
60
mean, g
3338
3286
NS
SD, g
321
271
NS
*t-test on sample means (P<.05).
aF-test ratio on sample variance FDD Feed dump location SD= standard deviation
END End location Sig= significance (P&.05)
PND All birds penned
FXD Fixed quantity

61
TABLE 3-6. Effect of sample location (FDD vs. END) on mean
breeder hen and pullet body weight gain (Exp. 3)
Trial
1
Trial 2
Sample
Age
interval
FDD
END
FDD
' END
type
(Age
, wk
; Time)
(g)
(g)
(g)
(g)
Breeder
hen
PND
(36;
AM)
to
(38;
AM)
66
-141
141
16
FXD
(36;
AM)
to
(38;
AM)
77
-159
142
-16
PND
(36;
AM)
to
(38;
PM)
58
-105


FXD
(36;
AM)
to
(38;
PM)
42
-99


PND
(38;
AM)
to
(38;
PM)
-8
36


FXD
(38;
AM)
to
(38;
PM)
-35
60


Pullet
PND
( 8;
AM)
to
(10;
AM)
135
186
167
160
FXD
( 8;
AM)
to
(10;
AM)
141
188
167
143
PND
( 8;
AM)
to
(10;
PM)
92
127


FXD
( 8;
AM)
to
(10;
PM)
84
122


PND
(10;
AM)
to
(10;
PM)
-43
-59


FXD
(10;
AM)
to
(10;
PM)
-56
-67


1 Age interval= 36 wk of age AM weighing to 38 wk of age AM
or PM weighing.
FDD= Feed dump location
END= End location
PND= All birds penned
FXD= Fixed quantity
SD= Standard deviation
Sig= Significance (P<.05)

62
TABLE 3-7. Classification of suspect outliers as true
outliers by testing mean body weight with an outlier
interval ( 3*SD) for broilers, pullets and breeder hens
(Exper. 3)
Trial
(no.) Age
N
Mean
(g)
3*SD
(g)
Outlier
Interval
(g g)
Suspect
(no.)
Actual
(no.)
Broilers
1
40 d
316
1683
629
(1054,
2312)
4
0
2
38 d
165
1556
566
( 990,
2122)
1
0
3
38 d
166
1615
603
(1012,
2218)
1
0
Breeder hens
1
36 wk
138
3339
776
(2563,
4115)
0
0
2
36 wk
147
3373
896
(2477,
4268)
2
2
1
38 wk
128
3300
998
(2303,
4298)
2
1
2
38 wk
128
3443
980
(2462,
4423)
4
1
Pullets
1
8 wk
218
851
350
( 501,
1202)
7
2
2
8 wk
213
863
390
( 473,
1252)
9
0
1
10 wk
164
1009
434
( 575,
1444)
12
0
2
10 wk
162
1026
471
( 555,
1497)
13
3

TABLE 3-8. Effect of sample size on mean and variance of
body weight for broilers, pullets and breeder hens.
63
N
Mean
SD
N
Mean
SD
Breeder
hens
10
3560
233
10
3451
194
20
3465
301
20
3363
244
30
3433
382
30
3391
249
40
3394
360
40
3386
291
50
3411
343
50
3373
275
60
3414
333
60
3385
261
70
3387
326
70
3390
268
80
3384
316
80
3378
257
90
3387
305
90
3368
256
100
3387
297
100
3339
265
110
3357
318
110
3344
261
120
3353
309
120
3347
261
130
3364
312
130
3344
270
140
3364
320
140
3338
259
Broilers
Pullets
20
1707
161
20
870
123
40
1718
187
40
889
126
60
1702
198
60
885
113
80
1693
195
80
866
112
100
1687
201
100
862
111
120
1690
198
120
855
132
140
1693
201
140
859
128
160
1685
199
160
857
124
180
1680
200
180
860
119
200
1683
202
200
861
116
220
1683
212
220
853
117
240
1689
212
260
1690
211
280
1692
206
300
1676
206

64
FIGURE 3-1. Effect of early feeding schedule and time of
weighing on broiler breeder female body weight (Exp. 1).
FIGURE 3-2. Cyclic changes in non-laying breeder female body
weight, on an early or late feeding schedule.

65
FIGURE 3-3. Frequency distribution of confidence intervals for
a fixed quantity of birds excluding outliers (A) and all birds
penned-up in a flock (B)

CHAPTER IV
THE EFFECT OF SEVERE FEED RESTRICTION
DURING THE REARING PERIOD ON FEMALE
BROILER BREEDER REPRODUCTIVE PERFORMANCE
Introduction
Early studies that examined the effect of feed
restriction on reproductive performance utilized ad libitum
feeding as the bench mark or control group in their
experimental designs. A generalized model illustrating this
effect was proposed by Bullock et al. (1963), where they
postulated that the only response to restricted feeding is a
delay in sexual maturity, characterized by the displacement
or shifting of the production curve to older ages. Since
then, numerous research projects have shown that relative to
ad libitum controls, feeding programs that restrict the feed
intake of broiler breeder females during rearing will delay
sexual maturity (Lee et al.. 1971; Harms et al.. 1979;
Leeson and Summers, 1982), increase initial egg size (Blair
et al.. 1976; Leeson and Summers, 1982), decrease the number
of doubled-yolked eggs and therefore increase the number of
settable eggs (Fuller et al.. 1969; Chaney and Fuller, 1975;
Christmas and Harms, 1982; Hocking et al.. 1989; Katanbaf et
66

67
al., 1989b), increase livability (Lee et al.. 1971; Wilson
and Harms, 1986, Katanbaf et al.. 1989a), increase fertility
and hatchability (McDaniel et al.f 1981b; Bilgili and
Renden, 1985), and improves egg production (Leeson and
Summers, 1982; McDaniel, 1983; Wilson and Harms, 1986;
Hocking et al.. 1987; Katanbaf et al.. 1989b). These
effects will also be influenced by photoperiod, temperature
and other environmental factors that can alter the
reproduction process.
The primary breeder companies currently recommend
various degrees of feed restriction for their particular
strain which permit a relatively narrow range of growth
curves to be followed in different environments. The
optimality of these prescribed standards are of issue and
raise interest in feed allocations below current
recommendations (severe restriction).
If the overall objective of the breeder manager is to
maximize the number of placeable chicks per hen housed over
a normal production period, then the optimal growth curve
and corresponding feeding program for a particular strain
must be identified. The growing consensus is that current
recommendations lead to an overweight breeder flock that
does not meet this objective.
Therefore, the overall objective of this experiment was
to evaluate the breeder's recommended growth curve by
determining the relationship between various degrees of

68
severe feed restriction (relative to breeder
recommendations) and subsequent effects on the more specific
evaluation criteria: body weight, sexual maturity, mortality
and other hatching egg production parameters that impact on
the production of placeable chicks per hen housed.
Materials and Methods
Stock and Management
Male and female Arbor Acres strain broiler breeders,
hatched in-season at a commercial hatchery (September, 1987)
and vaccinated for Marek's disease before placement were
used in this experiment. A total of 860 day-old female
chicks were randomly placed into 20 litter-floor pens of an
open-sided house, Each 3.1 X 3,6 m pen was equipped with an
automatic waterer for ad libitum drinking and three pan type
feeders. Male chicks were group reared separately in a
litter-floor pen of an open sided-house and fed according to
breeder recommendations. At 20 wk of age all males were
individually weighed and 60 males, weighing between 2650 and
2950 g, were randomly placed 3 per female pen. sixty
replacement males (12 per treatment) were randomly placed in
pens in a separate house and maintained on respective feed
treatments. All birds were beak trimmed and vaccinated for
fowl pox at 10 d of age. Birds were vaccinated for
Newcastle disease and infectious bronchitis at 2, 5, 12, and
15 wk of age, and avian encephalomyletitis and fowl pox at

69
10 wk of age. Chicks were reared under natural daylight
conditions until 20 wk of age, then daylength was abruptly
increased from ca. 12 h to 15 h by supplementing with
incandescent light, ca. 22 lux at bird level, from 0430 h to
1930 h, E.S.T.
Feed Treatments
Birds were fed ad libitum until 2 wk of age and
restricted daily during the third week on a starter diet
(Table 4-1). All birds were fed on a skip-a-day basis a 16%
grower diet from 4 through 8 wk, a 12% grower diet from 9
through 15 wk, and a 16% grower diet from 16 through 19 wk
of age. Five feed treatment groups based on a standard
feeding program were used. The feed treatments were
designed to have body weight follow growth curves over the
life cycle that were: 8 percent above the breeder
recommended standard curve (+8%); standard (STD), which
approximated the breeder's standard curve; and 8 (-8%), 16
(-16%) and 24 (-24%) percent below the standard curve. Feed
allocations for the STD treatment were derived from average
weekly body weight estimates and all other feed treatments
adjusted quantitatively. Daily feeding of a laying diet
began at 20 wk of age, where the nutrient intake, other than
energy provided per bird per day, was based on current
recommendations (Wilson and Harms, 1984). This intake
furnished for the STD treatment 20.6 g protein, 754 mg
sulfur amino acids, 4.07 g Ca, 683 mg total P, and 170 mg

70
Na, per bird per day (Table 4-2). Adjustments in diet
formulation and allocation were made weekly based on level
of body weight gain and egg production.
Production,Measurements
Egg production and mortality records were kept daily.
Egg production was summarized by phase of maturity, that is,
pullet (1 d to 5% production) or breeder hen (5% production
to 65 wk of age). Average body weight was determined weekly
for each pen by weighing four groups of ca. 8 females and
one group of 3 males through 45 weeks and then bi-weekly
until 62 weeks of age. Average body weight of the STD -
treatment was compared with a target body weight recommended
by Arbor Acres for a particular age, and a feed allocation
made. Feed allocations for all other feed treatments were
quantitatively adjusted from this allocation to STD.
Eggs were collected three times daily, classified as
double-yolked or normal and stored in an egg cooler at 13 C.
Production was recorded daily and summarized by 14 d
periods. Average egg weight was determined weekly by
Individually weighing all normal eggs from one day's
production. Specific gravity was determined once per 4 wk
period, from 30 through 62 wk of age, by weighing eggs
individually then, storing one day's egg production
overnight and the next morning using the saline flotation
method with solutions set at intervals of 0.0025 g/l*
Fertility and hatchability were determined every 4 wk from

71
32 to 64 wk using four days production, ca. 100 settable
eggs, from each pen and set according to normal incubation
procedures.
ResearchPeriod and Environment
The relationship of average weekly temperature (highs
and lows), and hours of daylight to the research period is
illustrated in Figure 4-1. Birds were hatched in September,
1987 and commenced production in early March, 1988. The
onset of production coincided with increasing temperatures
and hours of natural daylight.
Experimental Design and Statistical Analysis
The experimental design was a randomized complete block
of five pens replicated 4 times and containing 36 female and
3 male broiler breeders from 28 wk until termination (less
female mortality). The experimental unit was the pen.
Forty-three females were started in each pen with seven
females removed for analysis of physical attributes by 28 wk
of age. The five feed treatments were replicated four times
into blocks that minimized experimental error caused by
temperature or natural daylight gradients within blocks
while maximizing their effects among blocks. Data analysis
utilized a linear statistical model for a randomized
complete block design:
= U + Ti + Bj + Eijk
where U = overall mean; Tt = fixed effect of feed treatment
and i 1, 2, ...5; B.¡ = fixed effect of pen blocking and

72
j 1/ 2, ...4; and EiJk = residual effect. When differences
among treatments were obtained, comparisons among means were
made by using the Waller-Duncan K-ratio test and were
considered significant if P < .05 (SAS, 1985). Data on
flock uniformity were analyzed using the general linear
models procedure (SAS, 1985). Differences in flock
uniformity were evaluated by the F-test ratio of variances.
Pearson's product-moment correlations were determined
between hatchability and fertility, and between specific
gravity and egg weight as a measure of linear association
(SAS, 1985).
Results and Discussion
Body Weight and Uniformity
Growth of the STD fed birds throughout the rearing and
breeder periods approximated the growth curve recommended by
Arbor Acres, the primary breeder (Figure 4-2). Growth
curves resulting from all other feed treatments paralleled
STD through 62 wk of age. Some convergence in body weight
during the latter half of the production cycle did occur
especially between the -24% and -16% treatments. As
expected, the effect of feed treatment on mean body weight
at 20 wk of age was significant (Table 4-3) with the -24%
birds being 520 g lighter than STD. Uniformity, as measured
by the coefficient of variation, was significantly better
for the -8% treatment only. A possible trend towards poorer

73
uniformity for the most restricted birds was suspected but
not substantiated. Blair et al. (1976) and Lee et al.
(1971) reported that an apparent disadvantage to feed
restriction was a possible negative effect on flock
uniformity. The effect of feed treatment on mean body
weight was still significant through 62 wk of age and the
-24% treatment maintained a mature body weight 255 g lighter
than STD. This was similar to findings by Brody et al.
(1980) who showed that after severe feed restriction, body
weights remained about 25% lighter than the mature body
weights of a control group. Uniformity at 62 wk improved
from 20 wk levels indicating that body weight distributions
seem to stabilize as the flock achieves a mature body
weight. Shank length was significantly and permanently
decreased by the -16% and -24% treatments (Table 4-3),
which indicates a stunting of the birds mature frame size.
Flock Maturation
Feed treatment had a significant effect in delaying the
onset of flock maturity (50% production). Mean age and body
weight at 50% production for each treatment are presented in
Table 4-3. To test the hypothesis that a reduction in body
weight will delay flock sexual maturity, the dependent
variable body weight (Y, kg) was regressed on the
independent variable age (X, days) at 50% production (Figure
4-3). The resulting negative linear regression equation,
Y = 5.737 .0137 (X),
Std. Err. (.426) (.002)
Prob. .0001 .0001,

74
indicates that for every 13.7 g decrease in body weight,
within the range of body weights and ages at flock maturity
found in this experiment, there was a corresponding delay in
flock maturity by 1 day. The resulting negative correlation
(r = -.84) was significant and is in agreement with findings
by Pearson and Herron (1982b) who also reported a
significant negative correlation (r = -.88) between these
factors.
Mortality
Mortality was not affected by feed treatment over the
life of the flock or when analyzed by pullet or breeder hen
phase of growth (Table 4-3). The levels of mortality for
all treatments were low compared to levels commonly found in
industry. Difficulty in detecting differences among
treatments was due to high levels of between-replicate
variation. There was a trend, although not significant, for
the -24% birds to have higher mortality in the pullet
rearing period and lower mortality in the breeder hen laying
period. This trend would be in agreement with observations
made by Pym and Dillon (1969, 1974) who noted that the net
effect of high rearing and low layer mortality would be no
difference in overall mortality, bee et al., (1971) cited
numerous reports of lower mortality during the laying period
in birds restricted during rearing. From an economic
perspective this would be an advantage due to the higher
value associated with the breeder hen.

75
Production Performance
The average hen-day production response to feed
treatment is illustrated in Figure 4-4. Generally, there
was a delay in sexual maturity which was proportional to the
level of feed restriction. The -16% and -24% feed
treatments had a slower rise to peak production, perhaps due
to poorer flock uniformity at that time. The production
response to all feed treatments peaked at ca. 82 to 84% and
the most restricted birds (-24%) remained at higher levels
of production from 40 through 65 weeks of age.
Average hen-day production to the common age of 64 wk
was significantly lower for the -16% and -24% treatments
(Table 4-4). These treatments were in production 8 and 15
days less than STD, respectively. However, at 64 wk of age
the -24% treatment was still at 63.4% production which was
11.5% higher than STD and represented the level of
production of STD some 10 wk earlier. This implies that
production would be likely to continue at acceptable levels
to industry for several more weeks. Moreover, there was no
significant difference in mean hen-housed production between
the -24% and STD treatments to 64 wk of age. Although
mortality was not affected by treatment the timing of
mortality relative to the production cycle was a
contributing factor to there not being differences in hen-
housed production.

76
Hen-day production of double-yolked eggs as affected by
feed treatment is illustrated in Figure 4-5, Proportional
increases in feed restriction resulted in proportional
decreases in hen-day production of double-yolked eggs. The
-24% treatment had significantly lower production of double-
yolked eggs than STD (Table 4-4). Katanbaf et al.. (1989b)
showed that a standard feed restriction program will produce
fewer double-yolked eggs than an ad libitum feeding programs
by a difference of 3,5 to 4.0 times. The incidence of
double-yolked eggs has been shown to be both strain and
season related (Christmas and Harms, 1982).
Hatching eggs per hen housed did not differ
significantly among feeding programs (Table 4-4). The data
presented in Table 4-5 compares production cycles by
chronological and physiological age. Data based on
physiological age was determined by adjusting the first day
at 5% production for each replicate to be the start of the
production cycle. This adjustment permitted a direct
comparison of the production cycles by discounting treatment
effects for the delay in sexual maturity (time). Comparison
of the -24% and STD production response to feed treatment,
adjusted for time, revealed no differences between these
treatments.
Egg Characteristics
The effect of the STD and -24% feed treatments on mean
egg weight and specific gravity during the production period

77
is illustrated in Figure 4-6. Generally, the -24% egg
weights were proportionately lighter and in parallel with
STD as the flock aged. By 58 wk of age egg weights
converged and no significant difference in egg weight could
be detected (Table 4-6) even though the body weights were
significantly different at this time. No differences were
found in egg weights pooled over the production cycle. The
normally arc-shaped egg weight curve appeared to flatten for
all treatments from wk 38 through 52, which corresponded to
the period of highest ambient temperatures.
Measurements on specific gravity exhibited similar but
reversed trends from egg weight. The -24% treatment had
proportionately better shell quality as specific gravity
values paralleled STD. No difference between treatments on
specific gravity or egg weight measurements could be
detected during early or late stages of the production
cycle.
The correlation coefficients between egg weight and
specific gravity are presented in Table 4-6, with their
corresponding probabilities of significance. Correlations
within treatments and pooled over the production cycle
revealed that all feed treatments had similar and highly
significant negative correlations. Correlations among
treatments characterize the age effect on these two
parameters. The positive correlation at 30 wk of age is due
to the delay in the start of the production cycle for the

-24% treatment. At this age, specific gravity values are
increasing for the -24%, whereas, the values for STD have
already peaked and are decreasing. At the end of the
production cycle, egg weights converged and an improvement
in specific gravity was found which weakened the negative
correlation between these parameters. This could be
explained, in part, by the return of cooler ambient
temperatures.
Fertility and Hatchability
Data presented in Table 4-7 demonstrate that
quantitative differences in feed restriction, even severe
feed restriction, did not have a significant effect on
fertility or total hatchability at any age. Moultry (1983)
reported lower levels of fertility and hatchability from
those birds on severe restriction during rearing and lay.
Feed Usage
Cumulative intake of feed, crude protein (CP) and
metabolizable energy (ME) are presented in Table 4-8 on a
chronological and physiological basis. Proportional
differences in quantities of feed, CP and ME for all
treatments were a result of the feed allocation program
which was used to maintain parallel growth curves. When
measured to the common chronological age of 65 wk the -24%
treatment consumed 5.02 kg less feed, .71 kg less protein,
and 15.16 Meal less energy per hen housed for growth,
maintenance and production than did the STD. On a

79
physiological basis the quantities of feed required for
growth and maintenance during the pullet phase was .68 kg
less for -24% than STD. Furthermore, the quantity of feed
consumed during the production period (breeder hen) was 4.33
kg less for -24% than STD.
The -24% treatment required numerically less feed per
dozen hatching eggs on a hen housed basis than STD (Table 4-
8). This difference was not significant due to levels of
between-replicate variation caused by the interaction of
feed treatment and environment on the initiation of
production. Moultry (1983) reported that the lowest level
of feed/dozen eggs resulted from a feeding program that was
io% above standard during rearing then 10% below standard
during lay. He found significant and proportional decreases
in feed/dozen eggs during the production period as feed was
restricted from 10% above to 15% below standard.
In summary, the results of this study indicate that
feed restriction levels below current recommendations can be
used with broiler breeder females without significantly
affecting fertility, hatchability, mortality or average egg
weight. The levels of severe feed restriction used in this
study produced a bird with a lighter mature body weight and
a smaller frame size. This bird consumed less feed without
significantly reducing the number of hatching eggs per hen
housed at a common age, when compared to birds fed on a
standard feeding program.

80
TABLE 4-1. Composition, calculated nutrient content and age
used for the starter and grower diets
Starter
Grower
Grower
21% CP
16% CP
12% CP
Ingredient
(1-3 wk)
(4-8/16-19 wk)
(9-15 wk)
%
Yellow corn
65.53
77.43
87.25
soy (49%) #
31.15
18.84
8.80
Dical Phos
1.23
1.60
1.92
Limestone
1.09
1.13
1.03
Salt
.40
.40
.40
Vit-Min**
.50
,50
.50
Amprolium
.05
. .05
.05
BMD40 @50g/ton
.05
.05
.05
Calculated Analysis ***
Protein, %
21.17
16.21
12.17
ME, keal/kg
2976
3081
3171
Contains 22% Ca and 18.5% P.
Supplied per kg of diet: 6600 IU vitamin A: 220 ICU
vitamin D3; 2.2 mg menadione dimethyl-pyrimidinol; 4.4
mg riboflavin; 13.2 mg pantothenic acid; 39.6 mg
niacin; 499 mg choline chloride; 22 meg vitamin B12;
125 mg ethoxyquin; 60 mg manganese; 50 mg iron; 6 mg
copper; 0.198 mg cobalt; 1.1 mg iodine; 35 mg zinc.
Calculations based on 3432 and 2460 keal/kg and 8.8 and
49% CP for corn and SBM, respectively.

81
TABLE 4-2. Daily nutrient intake of broiler breeders after
20 weeks of age
Nutrient
Daily intake / bird
Protein, g
20.6
Sulfur amino acids, mg
754
Methionine, mg
400
Lysine, mg
938
Arginine, mg
1379
Tryptophan, mg
256
Calcium, g
4.07
Phosphorous, mg1
683
Sodium, mg
170
Vitamins2

Energy3

Expressed as total phosphorus.
2Levels of vitamins and trace minerals in finished feed met
minimum daily intake suggested by National Research Council
(1984) .
3Diets were formulated for feed intake of 109 to 204 g/bird
per day. Examples of energy intake are 301, 398, 495, and
636 kcal per day for diets formulated for 109, 137, 164, and
204 g/bird per day feed consumed.

TABLE 4-3. Effect of feed treatment on growth, development and mortality of breeder hens
Feeding program
Variable
+8%
STD
-8%
-16%
-24%
Growth
20 wk BWT, g
2261 26a
2103 +
23b
1935 +
19
1751 +
23d
1583 +
21*
20 wk CV, % *
14.0
13.6
11.9
16.6
15.9
62 wk BWT, g
3765 32a
3671 +
Q
CO
n
3567 +
34
3425 +
37d
3416 +
29d
62 wk CV, %
9.7
11.6
10.9
12.2
9.7
28 wk SHANK, mm
115.0 + .7*
113.7 +
. 9ab
114.7 +
. 8ab
112.5 +
. 9bc
110.9 +
1 lc
62 wk SHANK, mm
114.3 + .3
114.2 +
.3*
113.2 +
. 4b
112.1 +
.4
110.9 +
. 4d
Development (Flock maturation^
BWT 50% Prd., g
3157 + 28a
3049 +
36b
2964 +
37b
2809 +
8
2648 +
42d
2*
Age 50% Prd., d
190 + ld
197 +
le
205 +
2b
215 +
3*
219 +
Mortality
Life of flock, %
4.6 + 1.5a
5.7 +
1.8a
4.9 +
1.4a
3.8 +
1.3*
4.6 +
1 oa
Pullet phase, %
1.5 + .9a
3.8 +
2.9a
2.3 +
1.5*
1.5 +
1.5*
5.3 +
L £
.8*
2.4*
Breeder phase, %
7.6 + 1.9a
7.8 +
2.0*
7.8 +
2.0*
6.2 +
1.2*
4.0 +
BWT= Body weight
, CV= Coefficient of variation,
SHANK=
Shank
length.
F-test ratio
of variance (P<
.05) .
05
to

TABLE 4-4. Effect of feed treatment on breeder hen mean (+ SEM) production performance
Feeding program
Variable
+8%
STD
-8%
-16%
-24%
Hen-day prd
to 64 wk, %
Hen-day prd
at 64 wk, %
Hen-housed prd
to 64 wk, %
Hen-housed prd
at 64 wk, %
Hen-day prd
DBL-YLK, %
H.E. / H.H.
to 64 wk, no.
63.5
+
. 6a
63.1
-6a
63.3
6a
61.0
+
. 7b
61.0
+
. 7b
54.3
+
1.0
51.9
-8
58.7
+ l.lb
59.3
+
1.3b
63.4
+
1.1
61.4
+
. 5a
59.8
6a
60.0
6a
57.9
+
. 7b
59.8
+
. 7a
50.7
+
. 9cd
48.5
1.2d
53.4
+ 8bc
55.4
+
1.4b
61.7
+
1.4
1.23
+
.Ia
.8
.lab
.7
-lb
.5
+
.lbc
.4
+
lc
176 5a
172 + 5a
172 + 3*
166 + 4s
171 + 8s
a'd Means within a row having no common superscript are significantly different (P<.05).
H.E./H.H= Hatching eggs per hen-housed.
03
0J

TABLE 4-5. Effect of feed treatment on hen-day production for chronological and
physiological ages
Chronological
age
Physiological age*
Age
(wk)
+8%
STD
-8%
-16%
-24%
Week
Prd.
+8%
STD
-8%
-16%
-24
%
25
1.7a
8b
jbc
^bc
0C
1
10
.5a
9
43b
7.2bc
5.5
7
. obc
26
11.3a
6.
5b
3
.1
. 8d
0d
2
33
.9a
26
. 6b
14.7cd
13.8d
18
.7
27
36.3a
21.
9b
9
. 8
3
. 8d
1.0d
3
58,
.5a
47,
.0b
31.5C
26.3d
33,
. 8C
28
58.5a
42.
lb
23
. 5C
10
. 7d
4.3
4
72,
.0a
67,
.Ia
49. lb
38.1
50,
.lb
29
72.9a
62.
lb
38
.7
21
. 5d
11.4e
5
78,
.6a
75,
.7a
65.5b
50.6
63
.lb
30
79.4a
73.
lb
55
.5
35
. 3d
25.3a
6
81.
,1a
82,
,1a
72.4b
64.7C
68,
. 6bc
31
81.8a
81.
Ia
66
. 6b
45,
.3
40.8d
7
83.
,4a
82.
,2a
80.1a
75.2b
73,
,0b
32
84.1a
83.
5a
76.
. 6b
59,
. 8
57.5C
8
83.
4ab
84.
,4a
85.3a
80.2bc
78,
. 6
33
83.4a
82.
7a
81,
,5a
71,
. 6b
64.9C
9
82.
,4a
83.
,0a
82.8a
82.3a
81,
,4a
34
82.1a
83.
8a
82.
,7a
78.
,0b
71.6C
10
81.
,2a
80.
,6a
82.8a
83.6a
83.
,3a
35
81.6a
80.
4a
82.
,9a
82.
,6a
75.8
11
82.
,1a
83.
,1a
85.4a
82.1a
85.
,5a
36
81.3bc
82.
9b
85.
,6a
82.
. 7b
80.0C
12
79.
, 4b
83.
,4a
84.9a
84.9a
84.
,1a
37
79.8b
82.
9a
83.
,8a
83.
,0a
81.9ab
13
77.
, 9b
79.
48b
83.1a
80.3ab
82.
,8a
38
77.0
80.
7b
84.
,0a
83.
,3a
84.5a
14
76.
,2b
78.
4b
81.9a
80.5a
80.
,5a
39
76.2b
77.
5b
83.
,0a
82.
,6a
84.1a
15
75.
.3a
77.
,5a
78.1a
76.1a
75.
,9a
40
75.4C
79.
lb
79.
. 6b
78.
,9b
84.6a
16
72.
.5a
73.
,3a
75.8a
71.6a
74,
,5a
41
72.0d
74.
6C
77.
,0b
79.
,6a
81.7a
17
69.
4bo
67,
,0C
70.9abc
73.2ab
74.
,6a
42
68.0
67.
8C
73.
. 9b
72.
,3b
77.8a
18
62.
, 8b
68.
yab
73.9a
62.2b
72.
,3a
43
63.5d
68.
8
72.
,0b
73.
j^ab
75.7a
19
62.
,9b
71.
,0a
72.5a
60.3b
71.
,0a
44
64.0
67.
9b
71.
,1a
71.
,5a
74.1a
20
62.
. 7b
67.
,6a
69.8a
67. lab
70.
,3a
54
62. lb
61.
lb
65.
,3a
66.
,4a
65.8a
30
62.
l^be
60.
, 8C
66.2b
65.9bc
71.
,1a
64
54.3C
51.
, 9C
58.
. 7b
59.
, 3b
63.4a
35
59.
2ab
58.
. 5b
61.8ab
60.5ab
63,
,9a
Avg.
63.5a
63.
,1a
63.
,3a
61.
,0b
61.0a
Avg.
66.
,1a
66,
,3a
66.5a
64.7b
66,
,9a
Determined by adjusting the first day of 5% production for each rep. to be the start of the production
cycle.
a'd Means within a row having no common superscript are significantly different (P<.05).

Table 4-6. Effect of feed treatment on mean (+ SEM) specific gravity (SG) and egg weight
(EW), and the correlation between these parameters at various ages
Feeding program
Corr.
Age, +8% STD -8% -16% -24% Pooled Coef.
(wk) /Prob
30/SG
1.0812
+
.0005
1.0824
£
.0004
1.0820
£
.0005
^ab
1.0814
+
,0g04
1.0812
+
,0g08
1.0816
+
.0002
.262
30/EW
58.2
£
.6
58.2
£
.5
56.6
£
55.7
£
55.3
£
56.8
£
.4
.264
34/SG
1.0812
£
,0008b
1.0810
£
.0004b
1.0832
£
,0g03
1.0846
£
.0004
5b c
1.0837
£
.0004
1.0827
+
.0003
-.691
34/EW
63.4
£
.6
61.4
£
. 5b
60.5
£
59.9
£
58.9
£
.2
60.8
£
.4
.001
38/SG
38/EW
1.0780
66.0
1
£
.0005b
.6
1.0777
65.5
£
£
.0004b
^ab
1.0786
64.4
£
£
.0007b
2bc
1.0793
64.7
£
£
,0003b
6b
1.0805
63.0
£
£
.0005
. 4c
1.0788
64.7
£
£
.0003
.3
-.512
.021
42/SG
42/EW
1.0741
65.6
£
£
,0008b
.6
1.0744
65.8
£
£
,0007b
.8
1.0751
64.8
£
£
.0004b
.6
1.0764
65.1
£
£
.0002
.6
1.0766
64.0
£
£
.0006
.2
1.0753
65.1
£
£
.0003
.3
-.600
.005
46/SG
46/EW
1.0775
68.3
£
£
,0007b
.2
1.0773
66.9
£
£
,0004b
6b
1.0781
66.1
£
£
.0003b
^bc
1.0782
65.4
£
£
.0007b
6bc
1.0798
65.1
£
£
.0009
. 7
1.0782
67.0
£
£
.0003
.4
-.386
.093
50/SG
50/EW
1.0747
67.7
£
£
,0006b
.7
1.0752
67.6
£
£
0009b
.9
1.0750
66.9
£
£
.0006b
1.1
1.0782
66.9
£
£
.0005
.8
1.0771
65.7
£
£
. 0012b
.7
1.0760
66.3
£
£
.0003
.3
-.043
.856
54/SG
54/EW
1.0768
69.4
£
£
.0004
.4
1.0760
68.4
£
£
.0005
^ab
1.0758
67.8
£
£
.0003
8ab
1.0777
68.3
+
£ 1,
.0010a
,0a6
1.0775
66.8
£
£
.0005
. 6b
1.0767
68.1
£
£
.0003
.3
-.181
.444
58/SG
58/EW
1.0777
70.3
£
£
.0005
.3
1.0782
70.2
£
£
.0006
.2
1.0783
69.1
£
£
.0002
1.0
1.0790
69.2
£
£
.0008
.8
1.0788
69.1
£
£
.0010
.4
1.0784
69.6
£
£
.0003
.3
-.263
.263
62/SG
1.0785
+
.0008
1.0786
£
.0004
1.0786
+
.0004
1.0797
+
.0008
1.0798
+
.0011
1.0790
+
.0003
-.322
62/EW
72.5
£
.3
71.3
£
.6
71.4
£
1.0
71.2
£
.1
70.7
£
.5
71.4
£
.3
.166
Pooled
.000515
.7
/SG
/EW
1.0777
66.8
£
£
.0004b
.7
1.0779
66.1
£
£
,0004b
.7
1.0783
65.3
£
£
1.0794
65.2
£
£
.0004
.8
1.0794
64.3
£
£
.0004
.8
1.0785
65.0
£
£
0
.2
-.528
0
Corr.
coef. -.41 -.542 -.593 -.523 -.453
Prob .007 .001 0 .001 .006
ab Means within a row having no common superscript are significantly different (P < .05).
Corr. coef.= Pearson's product-moment correlation coefficient and probabilities of significance in parenthesis.
co
ui

Table 4-7. Effect of feed treatment on mean ( SEM) hatchability of all eggs set (Hatch)
and fertility (Fert) at various ages.
__ Feeding program
Age
, (wJc)
+8
%
STD
-8
%
-16%
24
%
Pooled
32
Hatch
82.0
+ 2.9a
84.0
3.1a
80.8
4-2.1
82.5
+ 3.3a
75.8

2.3a
81.0
*4" 1 2
Fert.
91.3
3.7a
94.8
.6a
92.0
4-2.7
90.5
3.3
90.5

3.2a
91.8
1.2
36
Hatch
87.0
+ 2.1a
92.0
+ 1.5a
86.8
+ 5.7a
84.0
2.9
91.0

.6
88.2
+ 1.4
Fert.
95.8
1.3
95.3
1.9a
94.5
2.9a
91.3
2.9
96.5
+
.7
94.7
.9
40
Hatch
86.0
+ 3.8a
88.3
1.8a
87.5
4 2.7
85.0
+ 4.2
84.5
+
3.0a
86.3
+ 1.3
Fert.
92.0
2.1a
95.3
1.3a
95.0
2. Ia
90.0
3.9
93.0

1.3a
93.1
1.0
46
Hatch
85.3
+ 4.0a
79.0
+ 2.7a
80.3
1.3a
83.8
+ 3.1
81.5
+
2.6a
82.0
+ 1.3
Fert.
90.0
3.2a
81.3
3.2
85.5
2.6a
89.5
2.4
85.0

3.5a
86.3
1.4
52
Hatch
85.3
+ 3.6a
83.0
+ 2.6a
82.8
+ 2.9a
82.5
+ 2.1
82.3

2.1a
83.2
+ 1.1
Fert.
91.3
1.7
90.0
3.6a
91.3
1.6a
89.5
3.8
86.8

1.8
89.8
1.1
56
Hatch
79.3
+ 3.4
80.0
+ 3.5a
74.0
4 2.5
81.8
+ 2.2
77.0
+
2.5a
78.4
+ 1.3
Fert.
91.8
1.3
93.5
2.9*
87.8
2.3
92.3
2.0
92.0
i
1.7
91.5
-9
62
Hatch
83.5
+ 4.0a
84.0
+ 3.0a
80.8
+ 2.2a
85.5
+ 3.3
82.8

2.0a
83.3
+ 1.2
Fert.
92.5
1.9
90.8
2.7a
91.8
1-8
90.0
+ 5.4
90.0
4
2.6a
91.0
1.3
64
Hatch
75.3
+ 1.4a
75.0
4- 4.0a
78.5
+ 2.5a
78.3
4.0
72.0
+
1.7a
75.8
+ 1.3
Fert.
89.8
1.8
93.0
4.4a
89.8
3.4
91.0
4.3
88.5

3.6a
90.4
1.5
Pooled
Hatch
82.9
1.2
83.2
+ 1.3a
81.4
+ 1.2
82.9
1.1
81.3
1*2
82.4
+ .5
Fert.
91.8
-8a
91.7
1.2a
90.9
.9a
90.5
1.2
90.3
1.0
91.0
.5
a,b Row means followed by different superscrips differ significantly (P<.05).
03
Cs

TABLE 4-
various
8. Cumulative
chronological
feed, crude protein and metabolizable energy
and physiological ages by feed treatment
intake per
bird at
Feeding program
+8%
STD
-8%
-16%
-24%
Chronoloaical age
20 wk
Feed, Kg
8.94
8.32
7.71
7.09
6.49
CP, Kg
1.38
1.29
1.20
1.10
1.01
ME, Meal
27.70
25.78
23.86
21.95
20.07
35 wk
Feed, Kg
25.55
24.03
22.63
20.94
19.28
CP, Kg
3.77
3.54
3.33
3.08
2.83
ME, Meal
76.63
72.07
67.88
62.81
57.85
65 wk
Feed, Kg
57.52
55.93
54.49
52.64
50.91
CP, Kg
8.18
7.94
7.74
7.48
7.23
ME, Meal
171.71
166.98
162.63
157.01
151.82
Physiological age
Rearing
phase, d
175
179
184
187
194
Pullet
Feed, Kg
13.22
12.73
12.58
12.35
12.05
CP, Kg
2.08
2.01
1.99
1.96
1.91
ME, Meal
39.71
38.20
37.64
36.85
35.90
Breeder
Feed, Kg
44.31
43.19
41.91
40.29
38.86
CP, Kg
6.10
5.93
5.75
5.52
5.32
ME, Meal
132.00
128.78
124.99
120.16
115.92
Life of
flock
FEED/DZHE, Kg
3.94
3.92
3.81
3.82
3.59
CO

88
RESEARCH PERIOD
FIGURE 4-1. Average weekly high (HI) and low (LO)
temperatures and hours of daylight (LIGHT) during the
research period.
FIGURE 4-2. Live body weight from hatching to 62 weeks of
age as affected by feed treatment.

BODY WEIGHT,
8!
FIGURE 4-3, Relationship between body weight (Y, g) and age (X, d)
as affected by feed treatment at 50% production (flock; maturity).

HEN-DAY PRODUCTION, C?0
90
FIGURE 4-4. Effect of feed treatment on hen-day production
(%).

91
AGE, £WEEKS}
FIGURE 4-5. Hen-day production of double-yolked eggs (%) as
affected by feed treatment.
AGE, CWEEKS}
FIGURE 4-6. Mean egg weight (g) and specific gravity (g/mL)
plotted over the production period for the STD and -24% feed
treatments.

CHAPTER V
CHARACTERIZING THE ONSET OF SEXUAL MATURITY
IN FEED RESTRICTED BROILER BREEDER FEMALES
Introduction
The prime objective of a broiler breeder feeding
program is to maximize the number of chicks/hen at the
lowest cost possible. Realization of this objective
requires that a breeder manager achieve a target body weight
at a target age and a high degree of flock uniformity (Arbor
Acres, 1985). The importance of targeting sexual maturity
is a practical issue where economic considerations are
usually of greater concern than the need to understand the
physiological changes that occur at this time. Yet, if the
art of targeting sexual maturity in feed restricted broiler
breeder females is to be successful, then the science must
be understood and used to an advantage.
Numerous studies have been undertaken to determine the
mechanisms involved in the neuroendocrine initiation of
sexual maturity. Brody et al. (1980) postulated that both a
minimum body weight and chronological age are required for
sexual maturity while noting that a minimum fat content
might be necessary as well. The effects of feeding and
lighting programs on sexual maturity of different strains
92

93
have been shown to be significant and demonstrate a need to
understand these responses for each strain of bird
(Christmas and Harms, 1982; Cave, 1984b; Soller et_al.,
1984a; Anthony et al.. 1989). Furthermore, the ability to
manipulate the onset of sexual maturity through feed
restriction and diet composition (Soller et al., 1984b), and
by photostimulation (Morris, 1967; Brake and Baughman, 1989)
have proven to be important tools for the breeder manager.
The pullet-layer transition period has been identified
as a critical stage in developing efficient breeder hens
(McDaniel, 1983; Cave, 1984b; Brake et al.. 1985). Protein,
energy and mineral requirements are changing rapidly as body
development and sexual maturity are synchronized with age.
Targeting sexual maturity is therefore a synchronization
problem, where development of the skeleton, lean body
tissue, fat deposits and chronological age ideally converge
at a point that predisposes the breeder hen for an efficient
production cycle. These physiological changes manifest
themselves through various physical attributes that can be
quantified and possibly used as feedback information for the
manager regarding the feeding and lighting programs.
Therefore, the objective of this experiment was to
characterize how these physical attributes associated with
sexual maturity would be affected by severe feed
restriction, as the female broiler breeder passed through
the pullet-layer transition period.

94
Materials and Methods
Stock. Management, Feed Treatments
Detailed descriptions of the strain, management
procedures and feed treatments have been presented (Chapter
IV). Briefly, 860 Arbor Acres strain of broiler breeder
chicks (hatched September, 1987) were reared in 20 litter-
floor pens of an open-sided house. Chicks were reared under
natural daylight conditions until 20 wk of age then
daylength was abruptly increased to 15 h by supplementing
with incandescent light from 0430 h to 1930 h, E.S.T.
Birds were fed ad libitum until 2 wk of age and
restricted daily during the third wk on a 21% starter diet.
All birds were fed on a skip-a-day basis a 16% grower diet
wk 4 through 8, a 12% grower diet wk 9 through 15, and a 16%
grower diet wk 16 through 20. After 20 wk of age all birds
were fed a breeder diet on a daily basis. Five feed
treatments based on a standard feeding program were designed
to follow growth curves that were; 8 percent above the
breeder standard (+8%) ,* standard (STD), which approximated
the breeder's standard curve; and 8 (-8%), 16 (-16%), and 24
(-24%) percent below standard.
Reproduction Traits Measured
Eighty females were randomly sampled every 2 wk from 16
through 28 wk of age and measurements on various physical
attributes made. Sixteen birds per treatment were
identified and weighed individually (BWT) on an electronic

95
scale to the nearest gram. Approximately 5 mL of blood was
obtained by cardiac puncture. Heparin was used as an
anticoagulant and blood samples were centrifuged at 1000 X G
for 10 min at room temperature. Total plasma lipid (LIPID)
was determined by the chloroform-methanol method (Folch et
al., 1957). Shank (tarsometatarsal) length (SHANK) was
measured with a Dekalb shank ruler to the nearest 1.0 mm;
pubic spread (distance between the pubic bones, ARCH) was
determined with a custom made ruler to the nearest 0.25 cm;
a subjective score of head development (comb and wattle
size, HEAD) ranging from 1 to 5, with 5 being the most
developed was recorded for each bird; and the height and
width of the comb (COMB) was combined into a comb factor
(cm'2) Four of those birds from each feed treatment were
killed (cervical dislocation) every 2 wk from 20 through 28
wk of age and the ovary (OVARY), oviduct (OVID), bursa of
Fabricius (BURSA), and abdominal fat pad (FTPD), including
the fat around the gizzard, were removed and weighed to the
nearest 0.1 g.
Statistical Analysis
Prior to analysis, absolute values for all physical
attributes measured were transformed to natural logarithms.
Data expressed as a percent of live body weight were
transformed to arc sine square roots (Gomez and Gomez,
1984), and then all data were subjected to analysis of
variance by using the linear statistical model for a

96
randomized complete block design. When differences among
treatments were obtained, comparisons among means were made
by using the Waller-Duncan K-ratio test (SAS, 1985).
Pearson's product-moment correlations were determined for
all variables as a measure of linear association (SAS,
1985). Three dimensional scatter plots of mean bi-weekly
values of each attribute measured were used to characterize
the AGE X BWT X TREATMENT effect on the onset of sexual
maturity (SAS, 1987).
Results and Discussion
Multidimensional scatter plots illustrating the effect
of feed treatment on various mean physical attributes
associated with the onset of sexual maturity are presented
in Figures 5-1 through 5-8. These plots demonstrate how
each attribute developed over time and in relationship with
body weight. For example, the effect of feed treatment
(Circle= +8%, Diamond= STD, Club= -8%, Heart= -16% and
Spade= -24%) on shank length (Z axis) relative to age (X
axis) and body weight (Y axis) is illustrated in Figure 5-1.
By locating a particular treatment symbol, i.e., spade, at
an early age, i.e., 16 wk, the feed treatment effect on
shank length and body weight is made evident by comparing
the spade (-24%) with the other treatment symbols.
Differences in shank length and body weight resulting from

97
feed treatment are discernable at any age and significance
among these differences are presented in Tables 5-2 and 5-4.
The attributes measured in this experiment were
classified as those increasing linearly with age, i.e.,
ARCH, BWT, COMB, FTPD, HEAD, and SHANK, and those that
abruptly increase near sexual maturity, i.e., LIPID, OVID,
and OVARY. The BURSA (Figure 5-9) was a special case that
was characterized by a quadratic response to aging with a
relatively rapid regression in absolute weight upon sexual
maturity. The effect of feed treatment on the development
of each attribute could be characterized by a delay,
relative to age, in the development of that attribute. The
effect relative to body weight was only apparent in the most
severe levels of restriction, i.e., -16% and -24%, where
development of individual attributes stabilized at lower
body weights. This observation can be explained by the
significant reduction in shank length for birds on the -16%
and -24% feed treatments. The severe feed restriction
retarded skeletal growth (frame size, Table 5-1) which
resulted in lowered body weights at sexual maturity. This
finding was similar to that of Leeson and Summers (1984) and
Brody et al. (1980).
The relationship between feed treatment and shank
length over the life cycle of the breeder hen is depicted in
Figure 5-10. These data demonstrate that: first, increasing
the levels of feed restriction had significant proportional

98
effects on shank length; second, maximum shank length was
attained at sexual maturity and plateaued to the end of lay;
third, compensatory growth was not fully attained in the
most severely restricted treatments; and fourth, there
appears to be a ridge line approximated by the -16%
treatment, below which permanent stunting of growth occurs.
Therefore, sexual maturity can also be characterized by
a plateauing of those attributes that serve as important
reserves to reproduction such as, the SHANK (mineral) and
FTPD (energy). Measurements on lean tissue development as a
reserve for protein would have been useful to this analysis,
unfortunately they were not measured. These findings were
consistent with those reported by Katanbaf et al. (1989c)
and Zelenka et al. (1987).
The correlation coefficients and probabilities of
significance for all combinations of attributes at various
ages are presented in Table 5-1. The significance levels of
the correlation coefficients of those attributes that
approximate sexual maturity (LIPID, OVID, and OVARY) with
those physical traits that are potentially measurable by the
breeder manager (ARCH, COMB, and HEAD), demonstrate that
comb measurements and subjective head scores could be used
for feedback information when targeting sexual maturity.
Even though the correlations with ARCH were significant,
measurements of ARCH would be less useful than measurements
of COMB or HEAD because of the gradual linear development of

99
the ARCH compared to the more abrupt change in correlation
significance of COMB and HEAD.
Bornstein et al. (1984) reported a high correlation
(r=,91) between abdominal fat and mean body weight at first
egg. The present study demonstrated that such levels of
correlation can exist even prior to sexual maturity and
possibly a decrease in correlation may occur as other
attributes (OVID, OVARY, COMB) increase their percentage of
relative body weight.
The primary focus of this study was the comparison of
the STD feed treatment to the most severe level of feed
restriction (-24%). Significant differences in BWT for
these two treatments at each age were expected and observed
(Tables 5-2 and 5-4). Furthermore, those attributes
exhibiting linear increases with age were all significantly
different at a common age, between these two treatments.
Attributes associated with an abrupt increase in absolute
values varied with age. Generally, at early ages, i.e., 20,
22, and 24 wk of age, no significant differences were found
in OVARY, OVID and LIPID values, but as sexual maturity
initiated there were significant differences in these
attributes.
Difficulty in establishing clear-cut trends in
attribute development were due to high variability and small
sample sizes for those attributes obtained from sacrificed
birds (Table 5-3 and 5-4). However, it appears that severe

100
feed restriction, at the levels used in this experiment, did
not alter the normal development of the bursa, fat pad,
pubic arch, comb or head score. Bursal involution was
significantly and negatively correlated with ovary
development (Table 5-1), suggesting that the bursa is
related to the onset of sexual maturity and thus not age
dependent. Feed restriction retarded, without altering, the
normal development and involution of the bursa (Table 5-3).
In summary, the main effect of feed restriction was to
delay the development of those attributes (investigated
here) associated with sexual maturity without significantly
altering their ultimate physiological values. The exception
to this finding was the effect of severe feed restriction on
shank length.

TABLE 5-1. Correlation coefficient (r) and the significance probability that the correlation
AGE
Trait
BWT
FTPD
LIPID
OVARY
OVID
(wk)
r
Prob.
r
Prob.
r
Prob.
r
Prob.
r
Prob.
20\22
BWT
.86
*
.71
*
.63
*
.48
.03
FTPD
.93
*
.44
.05
.32
.17
.40
.08
LIPID
.55
.01
.53
,02
.57
.01
.34
.14
OVARY
.64
*
.51
.02
.57
.01
.55
.01
OVID
.79
*
.82
*
.47
.04
.64
*
BURSA
.60
.01
.64
*
.18
.44
.34
.14
.57
.01
SHANK
.71
*
.53
.02
.46
.04
.54
.02
.46
.04
ARCH
.83
*
.80
*
.55
.01
, 66
*
.71
*
COMB
.73
*
.61
*
.19
.43
.40
.08
.55
.01
HEAD
.68
*
.66
*
.29
.21
.34
.14
.56
.01
24\26
BWT
.90
*
.66
*
.17
.48
.51
.02
FTPD
.92
*
.75
*
.29
.22
.55
.01
LIPID
.43
.06
.56
.01
.07
.78
.27
.25
OVARY
.24
.30
.23
.32
.62
*
.79
*
OVID
.32
.16
.38
.10
.73
*
.89
*
BURSA
.15
.53
.07
.76
.12
.62
-.15
.52
-.11
.64
SHANK
.62
*
.49
.03
-.12
.63
-.25
.28
-.16
.49
ARCH
.76
*
.81
*
.60
.01
.38
.10
.56
.01
COMB
.77
*
.72
*
.47
.04
.39
.09
.58
.01
HEAD
.64
*
.60
.01
.23
.34
.15
.52
.39
.09
28\ALL
BWT
.88
*
.54
*
.34
*
.58
*
FTPD
.79
*
.55
*
.35
*
.54
*
LIPID
.70
*
.61
*
.45
*
.67
*
OVARY
.33
.16
.29
.21
.30
.20
.83
*
OVID
.68
*
.47
.04
.57
.01
.80
*
BURSA
-.14
.56
-.15
.52
-.03
.89
-.47
.04
-.33
.16
SHANK
.63
*
.34
.15
.51
.02
-.13
.58
.20
.39
ARCH
.74
*
.60
.01
.59
.01
.54
.01
.75
*
COMB
.64
*
.57
.01
.39
.09
.35
.13
.42
.07
lmw: tr
HEAD
.69
TDn -P~*- ,
*
t tottah
.46
.04
.42
rvEJATVvr
.07
.36
.12
.55
.01
SHANK*shank length, ARCR=pubic spread, COMB=comb factor, HEAD=head score.
220, 24, and28 wk of age below the diagonal and 22, 26, and ALL (pooled) wk of age above the diagonal.
^Significance probability <.01.
101

TABLE 5-1. Continued
Age
Trait
BURSA
SHANK
ARCH
COMB
HEAD
Cwk)
r
Prob
r
Prob.
r
Prob.
r
Prob.
r
Prob.
20\22
BWT
.46
.04
.52
.02
.69
*
.43
.06
.60
.01
FTPD
.53
.02
.30
.20
.62
*
.49
.03
.63
*
LIPID
.24
.32
.44
.05
.23
.32
.12
.61
.27
.25
OVARY
.28
.25
.24
.31
.51
.02
.06
.81
.31
.18
OVID
.56
.01
.10
.67
.59
.01
.43
.06
.40
.08
BURSA
*
.99
.32
.18
.27
.25
.46
.04
SHANK
.26
.27
.54
.01
.10
.69
-.04
.87
ARCH
.51
.02
.48
.03
.47
.04
.44
.05
COMB
.52
.02
.35
.13
.62
*
.84
*
HEAD
.54
.01
.31
.18
.64
*
CO
CO
*
24\26
BWT
.33
.16
.48
.03
.64
*
.65
*
.68
*
FTPD
.33
.16
.18
.44
.64
*
.58
.01
.62
*
LIPID
.33
.16
.25
.28
.48
.03
.51
.02
.54
.01
OVARY
-.29
.22
-.17
.48
.53
.02
.22
.36
.40
.08
OVID
-.29
.22
*
.98
.72
*
.54
.01
.69
*
BURSA
.32
.17
.28
.23
-.17
.48
-.19
.44
SHANK
-.01
.96
.17
.48
.08
.73
.19
.42
ARCH
.12
.61
.27
.26
.40
.08
.53
.02
COMB
.03
.91
.43
.06
.82
*
.87
*
HEAD
.07
.78
.60
.01
.64
*
in
CO
*
28\ALL
BWT
.14
.18
.50
*
.73
*
.73
*
.75
*
FTPD
.13
.19
.30
*
.67
*
.68
*
.66
*
LIPID
-.11
.28
.45
*
.64
*
.58
*
.51
*
OVARY
-.36
*
-.09
.38
.61
*
.46
*
.46
*
OVID
-.29
*
.06
.54
.81
*
.68
*
.66
*
BURSA
.09
.40
-.16
.12
-.17
.10
-.07
.52
SHANK
.04
.86
.25
.01
.21
.04
.27
.01
ARCH
- .43
.06
.47
.04
.75
*
.76
*
COMB
-.31
.19
.44
.05
.65
*
.87
*
HEAD
-.26
.27
.48
.03
.78
*
.79
*
102

103
TABLE 5-2. Effect of feed treatment (mean + SEM) on various
attributes associated with sexual maturityr
Age Feed BWT FTPD LIPID
(wk) treat. (g) (g)(mg/mL)
20
+8%
2532

88a
70.8
+
4.4*
6.37
+
.38
STD
2156
4*
27b
50.1
+
4.7b
6.14

.34'
-8%
1945
+
32bc
29.8
4~
6.9C
5.89

.25
-16%
1752
4;
43c
12.7
+
4.6d
5.63

.13
-24%
1529

153d
7.7

6.4d
5.30
+
. 32
22
+8%
2651
49*
70.5
+
12.0
5,31

.11
STD
2334
t
39b
64.1
+
6.5*
5.03
+
.12
-8%
2182

23c
43.9
+
7.3*
4.99
j.
.16'
-16%
1941
+
48d
21.8
+
5.0b
4.51
+
.101
-24%
1710

39*
15.5
+
7.1b
4.54
t
. 171
24
+8%
2848
53*
127.0
+
18.9*
6.85
4.
1.23
STD
2835
+.
114
111.0
11.3*
4.75

.05'
-8%
2387
4;,
26b
57.2
+
3.9b
4.60

.08'
-16%
2250
+.
50b
59.3
+
11.3b
4.60
+
.14'
-24%
1891
+
16c
15.7
+
8.6C
4.45
.13'
26
+8%
3123
55
143.0
+
21.8*
12.10
+
2.78
STD
2950
+
160*
118.0
+
24.4*
10.40

1.03
-8%
2675
*4
64b
80.3
+
13.8be
5.05
+
l.ll'
-16%
2342
+
42c
31.6
+
5.8
4.65
+
.59'
-24%
2097
+
50d
29.7
+
15.3C
4.00

.32'
28
+8%
3018
113
104.0
+
o
o
M
17.60

2.72
STD
2886
+
131*
113.0
+
5.8
18.50
2.43
-8%
2713
79*
113.0
+
18.7*
14.50
+
4.18
-16%
2534
+
51b
75.2
+
18.2bc
9.15
+
2.071
-24%
2152
+
96
32.3
+
11.0
8.35

2.05
1BWT=body weight, FTPD=fat pad, LIPID=total plasma lipid are
only for those birds sampled and are not a treatment mean
for all birds.
'Means within a column and having no common superscript are
significantly different (P<05).

104
TABLE 5-2. Continued
Age Feed OVARY OVIDUCT
(wk)
treat,
(g)
(g)
20
+8%
53
. 03a
.53
+
.05
STD
.50
i
.04
.48

.05a11
-8%
.38

.03
* 30
t
.04
-16%
.40

0
.33
jh
. 03fco
-24%
.40

.11
.30
i
.07
22
+8%
1.02
+
.19
1.62
4*
.27
STD
. 66
Hh
* Q3b0
1.44
i
. 80th
-8%
.86

. 05ab
1.19
4*
,30th
-16%
.58
4.
.04
.57
,03b
-24%
.54

. 02c
.43
. Q4b
24
+8%
11.30

9.99
16.10
+
9.69
STD
.75
.04
3.21
. 78ab
-8%
.82
.02
1.20

. 27b
-16%
1.03
.24
7.37
+
3.97a53
-24%
.88

.03
.59

. 09b
26
+8%
3.52
nr
1.59b
15.80
4-
4.23ab
STD
6.83
+
4,16th
27.40

8.27
-8%
32.30
4,
18.50
35.40
11.80*
-16%
1.46
4.
. 32b
7.37
i
3.72bc
-24%
.81

. 29b
1.41

.80
28
+8%
34.80
+
14.40
52.10
7.66
STD
24.40
Hk
13. 40abc
37.40

12.50
-8%
3.85
+
1.47bc
20.30

6.37
-16%
37.10
Hh
20.70^
33.80
i
12.20
-24%
1.52
+
.46
5.16

3.85b
'Means within a column and age having no common superscript
are significantly different (P<.05).

105
TABLE 5-3. Effect of feed treatment on bursa weight (mean +
SEM) and relative proportion of bursa and fat pad to body
weight
Age Feed BURSA BURSA: BWT* FTPD:BWT
(wk) treat. (g) (g/g) (g/g)
20
+8%
2.63
.48a
.10
.02*
2.80
+ .14*
STD
2.53
.13
.12
.01*
2.15
.31ab
-8%
1.72
. 15ab
.09
+ .01b
1.52
-32b0
-16%
1.47
+ .19b
.08
.01b
.73
+ .25cd
-24%
2.02
.21*
.14
.01*
.45
.32d
22
+8%
2,61
*54*
.10
.Q2a
2.65
*43*
STD
2.48
.63*
.11
+. 03a
2.72
.25*
-8%
2.00
. 27a
.09
*01a
1.97
.31ab
-16%
1,78
+ .32*
.09
02*
1.10
.23bc
-24%
1.75
.22a
.11
01*
.90
. 39*
24
+8%
2.82
.39^
.10
*02*
4.42
+ .61*
STD
2.54
*15
,09
.01*
3.90
. 32*b
-8%
3,37
. 68a
.14
03*
2.40
. 17b
-16%
2.47
*30*
.11
+ .01*
2.62
+ 44ab
-24%
2.00
.09b
.11
o*
.85
.46c
26
+8%
2.88
, 30*
.09
.01*
4.58
. 62*
STD
1.77
.08bc
,06
+ ohc
3.97
62*
-8%
1.40
.12c
.05
+ 0
3.00
, 48ab
-16%
2.58
+ .66*
.11
+ .03*
1.35
+ .24bc
-24%
1.52
.17bc
.07
.01Ac
1.37
. 70c
28
+8%
1,05
*33*
.04
+ .01b
3.43
+ .59*
STD
1.60
.66a
.05
.02b
3.95
30*
-8%
2.29
. 74a
,08
+ .03ab
4.10
+ .58*
-16%
1.25
.51*
.05
+ .02b
3.00
+ .70*
-24%
2.48
. 73a
.12
04*
1.47
.43b
1BOT=Body weight: FTPD=Fat pad.
a'dMeans within a column and having no common superscript are
significantly different (P<.05).

TABLE
with
5-4. Effect of feed treatment (mean + SEM)
sexual maturity
on
various
physical
attributes associated
Age
Feed
BWT1
SHANK
ARCH
COMB1
HEAD1
(wk)
treat.
(g)
(mm)
(cm)
(cm' )
(no.)
18
+8X
2069
+
70
112.8 + 1.0a
2.44
+ ,10a
.21
+
,02a
1.6
+ ,2a
STD
1848
+
58
110.4 + 7ab
2.33
+ ,09a
.21
+
.01a
1.4
+ ,lab
-8X
1768
+
57b
108.1 + .9b
2.33
+ ,07a
.19
+
02a
1.4
+ ,1a15
-16X
1741
+
57b
108.1 + l.lb
2.32
+ 09.a
.22
+
02a
1.4
+ .l833
-24X
1514
+
55c
105.1 + .9
2.05
+ 06b
.14
+
,01b
1.1
-lb
20 +8X
STD
-8X
-16X
-24 X
2346 + 75a
113.5 +
1.0a,
2.70 +
05a
.29 +
,02a
2.0 +
2171 + 61a
112.2 +
gb
2.53 +
,05a
.26 +
.08
1.5 +
1856 + 56b
110.1 +
. 9b
2.27 +
. 06b
.20 +
.01
1.3 +
1677 + 55c
107.6 +
1.0d
2.14 +
.05"
.22 +
. 06bc
1.4 +
1625 + 60c
107.1 +
1.0d
2.19 +
. 09b
.18 +
.02
1.3 +
+8X
2486
+
74a
58ab
113.8
+
6;
STD
2336
+
112.3
+
81
-8X
2184
i
55b
112.4
+
1.2
-16X
2259
+
47d
111.3
+
. 9
-24X
1724
+
51d
107.9
T
.8'
2.78 +
,08a
.50 +
.06a15
2.8 +
.2'
2.70 +
06a
.56 +
07a
3.0 +
.2'
2.61 +
,05a
.39 +
04bc
2.2 +
.2
2.39 +
. 09b
.35 +
04d
1.9 +
.21
2.17 +
.09
.23 +
. 02d
1.4 +
.1'
+8X
2855 + 21a
115.0 +
,9a
3.31 +
,12a
.90 +
06a
3.3 +
STD
2782 + 61a
115.2 +
9
2.92 +
. 12b
.69 +
.07b
2.7 +
-8X
2353 + 64"
110.5 +
. 8b
2.67 +
. 08bc
.56 +
,08b
2.3 +
-16X
2259 + 47b
111.3 +
1.0"
2.58 +
.09
.48 +
,06d
2.5 +
-24X
2008 + 38
108.9 +
1.0b
2.31 +
. 05d
.35 +
.05d
1.8 +
+8X
3075 + 88a
115.3 +
.3a.
4.00 +
16a
1.06 +
,10a
3.2 +
.2b
STD
2806 + 88"
113.9 +
1.0
3.42 +
12k
1.11 +
,09a
3.8 +
,2a
-8X
2767 + 70b
115.7 +
8a
3.38 +
. 15b
.94 +
10ab
2.9 +
,lb
-16X
2382 + 76
111.3 +
1 0bc
3.28 +
. 14b
.70 +
. 07b
2.7 +
2b
-24X
2215 + 66
109.6 +
1.2
2.75 +
.12
.50 +
.07
2.3 +
.2
28 +8X
3146 + 54a
115.0 +
7a.
5.16
+
,09a
1.88 +
. i5a
4.7 + ,1a
STD
2924 + 81"
113.7 +
gBb
4.56
+
,10b
1.37 +
. 13b
4.1+ .2ab
-8X
2900 + 71b
114.7 +
gBb
4.11
+
. 17^
1.08 +
. 08b
3.6 + 2b
-16X
2612 + 48
112.5 +
1 0b
3.97
+
. 21d
1.13 +
. 17b
3.9 + 2b
-24X
2391 + 82d
110.9 +
1.1
3.58
+
. 27d
.60 +
.07
2.9 + .3
1BWT=Body weight;
COMB=height
X width;
HEAD=
=visual
score,
1 (least
developed)
to 5 (most
developed).
*dMeans within a column and having no common superscript are significantly different (P<.05) .
106

SHANK
107
o= + 8 7. 0= SID # = -8% v= -16% 0= -24?:
FIGURE 5-1. Effect of feed treatment on shank length (mm)
with respect to age (wk) and body weight (g)

FAT PAD
o
108
150 -
o= + 8 x 0 = s T D & = 8 % FIGURE 5-2. Effect of feed treatment on fat pad weight (g)
with respect to age (wk) and body weight (g).
28

ARCH
109
28
o= +8* 0 = STD eg, = 8 % <3? = -16% £= -2 4%
FIGURE 5-3. Effect of feed treatment on pubic spread or arch
(cm) with respect to age (wk) and body weight (g).

o= +8% 0= STD # = -8 5! <2= -16% 0= -2 4%
FIGURE 5-4. The effect of feed
5=most developed) with respect
(g)
treatment on head score (no.,
to age (wk) and body weight

COMB
111
2.5
28
O
= +8* 0= STD £= -8* -16% 0= -24%
_2
FIGURE 5-5. Effect of feed treatment on comb factor (cm )
with respect to age (wk) and body weight (g)

LIPID
112
0= +8?: 0= STD cg>= -8* (?= -16% 0= "24%
FIGURE 5-6. Effect of feed treatment on plasma total lipid
(mg/mL) with respect to age (wk) and body weight (g).

113
OVIDUCT
0= +8% STD <§> = -8% -16% 0= -24%
FIGURE 5-7. Effect of feed treatment on oviduct weight (g)
with respect to age (wk) and body weight (g).

o= +8% 0= STD <§>= -8 FIGURE 5-8. Effect of feed treatment on ovary weight (g)
with respect to age (wk) and body weight (g)

115
BODY YEISHT
TRT -oBg- A B ir~'v~~Â¥ C trr D 'ct-'tj FIGURE 5-9. Relationship of mean bursa weight (g) to body
weight (g) as affected by feed treatment (TRT a=+8%, B=STD,
C=-8% t D=-16% and E=-24%).

SHANK LENGTH
116
FIGURE 5-10. Effect of feed treatment on shank length (mm)
with age (wk).

CHAPTER VI
ECONOMIC ANALYSIS OF SEVERE FEED RESTRICTION
ON BROILER BREEDER PULLET REARING AND
BREEDER HEN HATCHING EGG PRODUCTION
Introduction
Growth and reproductive performance of broiler breeder
parent flocks have a direct and important impact on net
returns to a broiler integrator. Strain and Nordskog (1962)
regarded the breeding hen as the basic profit unit in the
integrated broiler industry. However, today, the breeder
parent has an indirect effect (transfer of genetic potential
to its progeny) on net returns that is more important than
the direct effect. The genetic capacity of the breeder
progeny to convert feed efficiently and yield more meat is
of primary economic importance to the broiler integrator.
Still, economic gains from increased broiler breeder
reproductive efficiency can be significant given the scale
of the broiler industry today.
Previous research on the biological effects of feed
restriction on female broiler breeder growth and
reproduction has indicated a number of technical advantages
to such feeding programs. Unfortunately, the economic
117

118
consequences of these effects are rarely determined.
Proudfoot and Lamoreaux (1973) compared "monetary returns"
resulting from full feeding, restricted feeding (75% of full
feed) and full feeding low protein diets (12.3%) during the
rearing period, as well as feed restriction during the
laying period of different meat-type strains. They found
that feed treatments used during the rearing period had a
significant effect on "monetary returns" from hatching egg
production with the restricted feeding program resulting in
higher monetary gains. The adult breeder feed treatment
(full fed vs. 90% of full fed) exhibited no significant
effect on either revenues or monetary returns over costs.
Proudfoot et al. (1984) evaluated the economic effect
of feed restriction during the laying period on the
performance of dwarf and normal broiler breeder hens.
"Monetary returns" calculated per hen housed showed that
normal breeder hens had significantly higher returns than
dwarf breeders. This was true despite a significantly lower
dwarf breeder level of feed consumption per dozen hatching
eggs produced. No difference in returns due to a level of
feed restriction 5% below standard could be detected. These
authors noted that because dwarf females can be housed more
densely than normal females, fixed costs of production could
be less per bird and may provide greater total returns to
the hatching egg producer than normal broiler breeder
strains housed at lower densities.

119
When dwarf broiler breeders were fed according to
standard feeding recommendations, differences in rearing
costs among strains were due to the incidence of mortality
and age at which death occurred (Proudfoot et al., 1985).
The hypothesis to be tested in this analysis can be
stated as follows: If broiler breeders are severely feed
restricted during the rearing period compared to current
recommendations and the resulting biological response is an
equivalent but delayed reproductive performance relative to
standard practices (Chapter IV), then economic returns to
the pullet grower, hatching egg producer and broiler
integrator from severe feed restriction will be increased
above levels currently derived from recommended practices.
The specific objectives of this analysis were to:
1) examine the effect of feed restriction on pullet rearing
cost structure; 2) determine the cost of extending the
rearing period (delayed sexual maturity) due to various
levels of feed restriction; 3) test the sensitivity of
pullet rearing average total costs to changes in component
costs; 4) compare average total costs of hatching egg
production for various degrees of feed restriction; 5) test
the sensitivity of average total costs of hatching egg
production to changes in component costs; 6) determine the
changes in cost structure during the rearing period due to
changes in the density of pullets per unit area; and

120
7) estimate the change in breeder hen laying cost structure
resulting from increased pullet rearing density.
Materialsand Methods
This analysis utilized experimental data (feed
consumption, body weight and hatching egg production)
obtained from a broiler breeder female feed restriction
experiment (Chapter IV) which formed the basis of the
biological response to severe feed restriction. The five
feeding programs used in this experiment were: 8 percent
above the breeder recommendations (+8%); standard (STD)
which approximated the breeder's guidelines? and severe feed
restriction of 8 (-8%), 16 (-16%) and 24 (-24%) percent
below standard.
The broiler breeder life cycle was divided into two
distinct accounting periods. The pullet rearing period
began at one day of age and ended at 5% production. The
breeder hen laying period began at 5% production and
continued until flock liquidation.
Mortality, and.Culling
Since the results of the feed restriction experiment
indicated no significant differences in either rearing or
laying period mortality due to feed treatment, the
assumption was made that cumulative mortality progressed at
a linear rate for both pullets and breeder hens. Pullet
mortality and culling during rearing (PMRT) was established

121
by projecting a linear increase in mortality at the
estimated base rate of .2% per wk starting from 1 wk of age
and resulting in 4, 5, and 6% cumulative mortality at 20, 25
and 30 wk of age, respectively. Similarly, a base rate for
breeder hen mortality and culling (BMRT) was determined by
linearly increasing mortality at the rate of .175% per wk
from the appropriate age at 5% production to 7, 7.9 and 8.7%
cumulative mortality after 40, 45, and 50 wk of production,
respectively.
Sensitivity Analysis and Prices
Sensitivity analysis indicates change in average total
costs for pullet rearing or breeder hen enterprises in
response to a 20% change in a component cost, with all other
costs held constant. The base price situation used in this
analysis was consistent with commercial prices found in the
Southeastern United States in 1988. Tables 6-1 and 6-2 list
the base price estimates and the corresponding +20%
adjustment made to the base prices.
Fixed Costs
Pullet rearing. Base female and male chick costs (CHK)
were estimated to be $1,72 and $2.75 respectively (Table 6-
1). Initial quantity purchased was adjusted for expected
mortality which allowed for a 9 to 1 female to male ratio of
survivors at 25 wk of age.
Breeder hens. Average total cost of a pullet survivor
reared to 5% production for a particular feed treatment

122
became the fixed cost in the laying accounting period.
Table 6-2 lists the pullet rearing costs for each level of
feed restriction based on pullet rearing costs detailed in
Table 6-1.
variable costs
Feed costs
Pullet (PFD) and breeder hen (BFD) feed costs for a
particular age were determined by accumulating the product
of the base feed cost ($.135/kg) for pullets or {$.125/kg)
for breeder hens and the appropriate quantity of feed
consumed by birds on a particular feeding program (Tables 6-
1 and 6-2). Cumulative feed consumption was obtained from
experimental data and feed costs included a provision for
medication and delivery costs.
Serviceand supervision costs
Pullet (PSRV) and breeder hen (BSRVj service and
supervision costs were determined for a particular age by
projecting a linear increase in cumulative costs at the
estimated base rate of $.013 /pullet/wk for the pullet
rearing enterprise or $.0075 /dozen hatching eggs (DZHE) for
the breeder hen laying enterprise. At these rates, the
total cost per pullet reared from l wk through 25 wk of age
was $.325 /pullet survivor and the total cost per DZHE
through 40 wk of production was $.30 /DZHE.

123
Contract payment costs
Pullet contract costs. Pullet-grower payment cost
(PPAY) was predicated on contractual arrangements. The
assumption was made that a pullet-grower would be paid at
the base rate of $.0275 per .0929 m 2 / wk for each flock
and that chicks would be housed at the base bird density of
.1626 m2 (1.75 ft2) per bird. From these standards,
cumulative pullet grower payments increased at the rate of
$.04812 /pullet/wk to a particular age.
Breeder hen contract costs. Cumulative hatching egg
data were obtained from each experimental treatment by
subtracting the double-yolked eggs from hen-day production
of total eggs and averaged into a weekly value. This
procedure was used due to a significant feeding program
effect on the incidence of double-yolked eggs (Chapter IV,
Table 4-4). Average weekly production of adjusted total
eggs was then further adjusted for commercial eggs, e.g.,
undersized, dirty, or cracked eggs, at an equivalent rate
(.0005%/wk) for all feeding programs, which allowed the
removal of 2% commercial eggs after 40 wk of production.
Cumulative production of hatching eggs was then adjusted for
breeder hen mortality and expressed as dozens of hatching
eggs per breeder hen survivor. This value for each feeding
program represents the output function in the production
process.

124
Payments to the hatching egg producer (BPAY) were
calculated based on the estimated contractual base rate of
$.30 /DZHE which included payment to the producer for egg
salvage (commercial eggs @ $.10 /DZ) and any potential
bonus.
Vaccination. Beak Trimming and Blood Testing Costs
Pullet vaccination, beak trimming, blood testing and
miscellaneous costs (PVAC) were determined by increasing
PVAC costs linearly from 1 wk of age at the rate of $.012
/pullet. At this rate the cumulative PVAC costs amounted to
$.30 /pullet at 25 wk of age.
Salvage Prices
Commercial egg salvage values (ESLV) received by the
integrator were determined for each feeding program by
multiplying cumulative commercial egg quantities at a given
age by the estimated salvage base price of $.10 /dozen.
Bird salvage values (BSLV) were determined for each
feeding program by multiplying the estimated salvage base
price of $.286 /kg of live bird by the average live body
weight of birds at a particular age.
Average Total Cost
Pullet rearing period. The total cost of rearing a
pullet was equal to the summation of fixed costs (CHK) and
variable costs (PFD, PPAY, PSRV and PVAC) for a particular
age. since the technical output of the pullet rearing
process is numbers of live pullets, livability data derived

125
from the linear pullet mortality function were used to
calculate average total costs (ATC/P) in dollars per pullet
survivor. This analysis projected the average total cost
and its component costs for each feeding program through 30
wk of age. This time frame captured the changes in cost
structure that occurred until birds on all feeding programs
achieved 5% production.
Breeder hen period. Economic evaluation of the breeder
hen period was made from two perspectives. The first
examined average total cost on a breeder hen survivor basis
(ATC/B), so that average cost could be examined
independently of production performance. Secondly, average
total cost was evaluated on the basis of a dozen hatching
eggs produced (ATC/E) which incorporated all aspects of the
production function into the breeder hen cost structure.
Results and Discussion
Pullet Rearing Period
The average cost structure of a standard (STD) pullet
rearing feeding program is illustrated in Figure 6-1.
Pullet average fixed cost (AFC/P) represents the pullet and
cockerel chick cost (CHK) at day of age adjusted for pullet
mortality. Pullet average variable cost for the combined
PPAY, PSRV and PVAC costs (AVC1/P) increased linearly
through 30 wk of age. Whereas, the average pullet variable
cost for feed (AVC2/P) increased linearly to 20 wk and then

126
increased at a relatively more rapid rate and surpassed all
other average cost groups by 29 wk of age. At ca. 27 wk of
age AVC1/P, AVC2/P and AFC/P converged to a common value
indicating that the average total cost of rearing a pullet
(ATC/P) could be divided into ca. 33% for CHK, 33% for PFD
and 33% for the combined costs of PPAY, PSRV and PVAC.
The effect of feeding program on PFD through 30 wk of
age is depicted in Figure 6-2. All feeding programs
increased at parallel rates with proportionately lower
cumulative feed consumption values for the higher levels of
feed restriction. The resulting feeding program effect on
ATC/P was a proportional reduction in PFD costs at a common
age. However, the magnitude of this reduction was not as
great when PFD costs and ATC/P were calculated to a common
physiological age, i.e., 5% production.
Five percent production occurred atea. 24, 25, 26, 27
and 28 wk of age for the +8%, STD, -8%, -16% and -24%
feeding programs, respectively. When ATC/P for each feeding
program were evaluated to a common age (Table 6-3),
proportional decreases in ATC/P occurred. Even though
pullets were a common chronological age they were not the
same in terms of physiological development. For example,
pullets reared on the STD feeding program were at 5%
production at 25 wk of age and at an ATC/P of $5.834.
Pullets reared on the -24% program incurred a lower ATC/P of
$5.436 at 25 wk of age, but these pullets were 3 wk away

127
from production. The cost of delaying sexual maturity
relates to holding pullets for this additional time.
Enterprise budgets for each feeding program are
presented in Table 6-4, with detailed average component
costs for rearing pullets to 5% production. Comparison of
the budgets revealed that at base prices, the cost of
delaying sexual maturity by ca. 3 weeks was $.170 per pullet
survivor or an average cost that was ca. 3% greater than STD
(1%/wk). Although the delay caused by feed restriction
decreased average PFD cost by $.090, increased PPAY ($.161),
PVAC ($.040), PSRV ($.044) and CHK ($.015) costs totaling
$.261 resulted in the net increase of $.171 per survivor.
The major average cost items in a pullet rearing
enterprise at 5% production were CHK, PFD and PPAY in that
order. PPAY is a function of pullet housing density and
contractual payment rates. Any change in pullet density
will not affect average cost to the integrator, unless
pullet density is increased beyond some tolerance limit and
results in increased mortality.
Figure 6-3 illustrates how sensitive ATC/P was to a 20%
change in a component cost at 20, 25 and 30 wk of age, while
on a STD feeding program. At 20 wk of age ATC/P are more
sensitive, as indicated by the steeper sloping line, to
changes in CHK than PFD costs. However, these costs became
equally important at 25 wk and ATC/P became more sensitive
to PFD at 30 wk of age. ATC/P did not appear to be

128
sensitive to PMRT at these ages or base levels used in this
analysis, even though it had a negative economic effect on
both CHK and PFD costs. Increased pullet density had an
important positive impact on ATC/P. The relative importance
being almost equal to CHK costs at the ages tested and
greater than PFD costs at 20 and 25 wk of age. ATC/P became
more sensitive to changes in pullet housing density with
age.
Sensitivity analysis performed on cost data from the
-24% program is illustrated in Figure 6-4 and revealed that
ATC/P was more sensitive to changes in CHK, costs at 20 and
25 wk than PFD costs. PFD, CHK and PPAY had nearly the same
relative impact on ATC/P at 30 wk of age. ATC/P was
relatively non-sensitive to PMRT at each age tested. At
base prices, the ATC/P for the -24% program was ca. .252,
.398 and .525 dollars lower than the STD program at the
common age of 20, 25, and 30 wk, respectively.
Figure 6-5 illustrates the change in magnitude of
P/ATC, at the base price situation, to a 20% increase in
PMRT, PPAY, PFD and CHK costs at 5% production for each
feeding program. Also plotted is the expected decrease in
P/ATC resulting from a 20% increase in pullet housing
density (DNSTY). This plot indicates that at 28 wk of age
(5% production for the -24% program) the ATC/P of $5,720 was
lower than the ATC/P of $5,834 recorded at 25 wk of age or
when the STD program reached 5% production. Savings from a

129
20% increase in pullet DNSTY offset the cost of delayed
pullet maturity. Under the scenario of increased pullet
DNSTY the pullet grower benefits from 3 wk of additional
revenue, the source of which was from PFD savings from the
-24% feed program.
Breeder Hen Period
Comparison of the breeder hen cost budgets for the STD
and -24% feeding programs (Table 6-5), shows a $.056 lower
ATC/B before salvage adjustments for the STD program. The
$.172 savings in BFD cost offset the added pullet rearing
(PUL$) cost ($.171) for the -24% program. The $.056
difference resulted from higher producer payments (BPAY) for
the production of hatching eggs. However, the $.056
difference increased to $.128 when salvage adjustments were
made, reflecting the heavier average body weight of breeder
hens on the STD program after 40 wk of production.
After 40 wk of production ATC/B for the STD and -24%
programs were $15,704 and $15,760, respectively, before
salvage adjustments were made. Generally, the ATC/B can be
partitioned into 40% for PUL$, 34% for BFD, 24% for BPAY and
2% for BSRV. Salvage adjustments (Table 6-5) represented a
potential recuperation of ca. 7-8% of ATC/B.
The combined average cost of rearing a pullet to 5%
production (PUI*$) and breeder feed (BFD) cost accounted for
74% of ATC/B. Mortality in the breeder house increased
total cost by $1.10 through lost feed and higher pullet

130
rearing costs, while lowering producer payments. BMRT was
costly on two accounts: first, by raising the ATC/B; and
secondly, by lowering average breeder hen production.
Average cost budgets on a ATC/E basis are presented in
Table 6-6 for various feeding programs. Relationships among
cost components are similar to those discussed on a survivor
basis. The slightly higher level of cumulative hatching
eggs for the -24% program was able to offset previous
differences in feeding programs due to salvage adjustments.
Essentially, the ATC/E for the STD and -24% programs were
the same. This implies that by 67 wk of age the additional
PL$ charges resulting from the -24% program can be offset
by BFD savings and increased production despite the salvage
advantage for the STD program.
It is important to note that a major difference between
these two feeding programs at this age was the level of egg
production. Experimental data resulted in a significantly
higher rate of production for the -24% program (63.4%) than
STD (51.9%) at 64 wk of age (Chapter IV, Table 4-4).
Prediction equations based on these experimental data
projected economically sound (decreasing ATC) levels of
production for the -24% program through 78 wk of age.
The changing relationship between breeder hen costs and
production (ATC/E) with age is illustrated in Figure 6-6.
This plot demonstrates that ATC/E for the STD program
reached a minimum ca. $1.17 /DZHE at ca. 72 wk of age*

131
After this age ATC/E for STD turned upward as continued
expenses (BFD and BMRT) overtook reduced production.
Whereas, ATC/E for the -24% program continued to fall
through 78 wk of age.
The effect of feeding program on ATC/E before salvage
adjustments were made is presented in Table 6-7 on a
chronological age basis. As the breeder hen aged, ATC/E
dropped at a curvilinear rate with the more restricted
feeding programs falling from a higher ATC/E value at 50 wk
of age. These differences among feeding programs represent
the ATC/E for delayed sexual maturity, which were
progressively overcome as the hen aged. Derived ATC/E for
70 and 75 wk of age suggest that the -24% program became
more economical (lower ATC/E) than STD by 70 wk. Figure 6-6
implies that under the assumptions made in this analysis the
-24% program achieved an equal ATC/E with the STD program at
ca. 67 wk of age (data projected for one week) and resulted
in a lower ATC/E than STD when production was projected
beyond this age.
Sensitivity analysis conducted on ATC/E data from STD
and -24% feeding programs revealed that after 40 wk of
production ATC/E was most sensitive to changes in BFD, PUL$,
BPAY and BMRT, in that order. A 20% change in component
BFD, PUL$, BPAY and BMRT costs on a STD feeding program
resulted in ATC/E to be changed by + .124, .088, .06 and
.016 dollars, respectively. Similarly, the -24% program

132
resulted in ATC/E to be changed by + .119, .089, .06 and
.016 dollars, respectively. The sensitivity of ATC/E to
changes in BFD and BMRT costs on STD and -24% feeding
programs is illustrated in Figure 6-7 and changes in PUL$
and BMRT in Figure 6-8. Sensitivity of ATC/E to changes in
BFD was affected by feeding program. The slopes of the BFD
lines in Figure 6-7 indicated that ATC/E was more sensitive
to increases in BFD costs on a STD program than when fed a
-24% program. However, under the situation of lowered BFD
costs the difference in feeding program was not as apparent.
Generally, the effect of feed restriction below current
recommendations on ATC/E through 40 wlc of production was a
slight shifting to lower values.
Pullet Housing Density
Justification for increasing the density of pullets in
a rearing house can be made for the more restricted feeding
programs on the basis of maintaining an equivalent bio-mass
(total live-bird weight) in a house. The average live
weight of pullets for a range of ages commonly used for
transferring pullets to a breeder house are listed in Table
6-8. The relative difference in these body weights indicate
that changing the pullet housing density by -7, 0, +7, +14
and +21% will result in ca. an equivalent bio-mass for each
feeding program at any probable transfer age.
The effect of changing pullet housing density on ATC/P
is illustrated in Figure 6-9. where ATC/P changed by +.085,

133
O, -.092, -.193 and -.300 dollars for the +8%, STD, -8%,
-16% and -24% feeding programs, respectively. This
increase in pullet DNSTY decreased the ATC/P at 5%
production for STD feeding program from $6.005 to $5.705 and
resulted in a decreased ATC/P of $.129 lower than STD.
Potential savings from increased pullet DNSTY is passed
directly to the breeder laying accounting period. Pullet
rearing costs (PUL$) represent ca. 42% of the average total
cost of producing a dozen hatching eggs. A comparison of
the effect of reducing PUL$ by $.30 on ATC/E for the STD and
-24% programs is illustrated in Figure 6-10. The lower PUL$
cost resulting from higher pullet DNSTY shifted the ATC/E
curve for the -24% program to the left. The magnitude of
this displacement was equivalent to ca. $.02 /DZHE.
Furthermore, the ATC/E for the two feeding programs reached
an equivalent value at ca. 62 wk of age, which was 5 wk
earlier than base housing density conditions (67 wk).
In summary, each wk of delayed sexual maturity from
severe feed restriction increased the ATC/P at 5% production
by ca. 1%. Decreased feed costs offset other pullet
variable costs at a common chronological age, but not when
evaluated to the physiological age of 5% production.
Increased pullet rearing costs, relative to standard, were
carried over into the breeder hen accounting period and
comprise ca. 40% of the ATC/B when evaluated through 40 wk
of production. When ATC were determined relative to

134
production (ATC/E), essentially no cost differences among
feeding programs were evident by ca. 67 wk of age.
Production estimates projected beyond this age indicated
that the most severe feed restriction program resulted in
decreasing ATC through 78 wk of age.
Severe feed restriction as a management technique has
the potential of lowering the ATC/E, if the assumption that
increasing pullet housing density to an equivalent bio-mass
with standard densities will not have any detrimental effect
to growth and production holds true.

135
TABLE 6-1. Base costs, production coefficients and 20%
adjustments used in sensitivity analysis of a pullet rearing
enterprise
Price
Situations
-20%
BASE
+20%
CHK cost1, $/pullet
1.622
2.026
2.432
Mortality
Pullet, %/wk
Cockerel, %/wk
.16
.41
.20
.50
.24
.60
Rearing feed, $/kg
* 108
.135
.162
Service &
Supervision, $/Surv.
.0104
.013
.0156
Pullet density,
m2/ pul let
Ft2/pullet
.1301
(1.40)
.1626
(1.75)
.1951
(2.1)
Grower rate,
$/m2/wk
$/Ft2/wk
.2368
(.0220)
.2960
(.0275)
.3552
(.0330)
XCHK cost= combined pullet ($1.70) and cockerel cost ($2.90)
at a 9:1 female to male ratio.

136
TABLE 6-2. Base costs, production coefficients and +
adjustments used in sensitivity analysis of a breeder
enterprise
20%
hen
Price
Situations
-20%
BASE
+20%
Averaae Pullet Rearina
Cost / survivor fat 5% Droduction}
a) +8%, $
4.596
5.745
7.894
b) STD, $
4.667
5.834
7.001
c) -8%, $
4.721
5.901
7.081
d) -16%, $
4.766
5.958
7.150
e) -24%, $
4.804
6.005
7.206
Breeder mort., %/wk
. 140
. 175
.210
Breeder feed, $/kg
.100
.125
.150
Producer pay, $/doz.
.24
.30
.36
Adjustment for
Commercial eggs, %/wk
.064
.080
.096
Service &
supervision, $/doz.
.0060
. 0075
. 0090
Hen salvage, $/kg
.229
.286
.343
Egg salvage, $/doz.
.08
.10
.12

137
TABLE 6-3. Average total cost of a pullet survivor reared
to common age on five feeding programs
Feeding Program
+8%
STD
-8%
-16%
-24%
Average Total Cost/
pullet survivor, $
20 wk
4.881
4.796
4.711
4.627
4.544
25 wk
5.967
5.834
5.700
5.567
5.436
30 wk
7.125
6.948
6.780
6.597
6.423

138
TABLE 6-4. Effect of feeding program on pullet rearing
average cost budget through 5% production, calculated at
base prices
Feeding Program
+8%
STD
-8%
-16%
-24%
Performance factors
Age, wk
24
25
26
27
28
Livability
Pullet, %
.952
.950
.948
.946
.944
Cockerel, %
.880
.875
.870
.865
.860
Feed, Kg/Surv.
12.96
12.98
12.83
12.61
12.31
Averacre Fixed
Costs /
Pullet survivor AFC/P1
Chick, $
2.152
2.158
2.163
2.169
2.173
Averacre Variable Costs
/ Pullet
survivor (AVC/P)
Feed, $
1.750
1.752
1.732
1.702
1.662
Grower pay, $
1.213
1.266
1.320
1.373
1.427
PVAC1, $
.303
.316
.329
.343
.356
Service &
supervision, $
.328
.342
.357
.371
.386
Averacre Total
Cost / Pullet survivor (ATC/P)
ATC/P, $
5.745
5.834
5.901
5.958
6.005
1PVAC= Pullet vaccination, beak trimming, blood testing and
miscillaneous costs.

139
TABLE 6-5. Effect of feeding program on breeder hen average
cost budget through 40 weeks of production, calculated at
base prices and expressed as dollars per survivor
Feeding Program
+8%
STD
-8%
-16%
-24%
Performance factors
Age, wk
64
65
66
67
68
Livability1, %
.93
.93
.93
.93
.93
Feed, kg/Surv.
45.40
44 >65
44.33
43.72
43.28
Hatching eggs,
doz/surv.
13.000
13.295
13.640
13.130
13.480
Averacre Fixed Costs
/ Breeder hen survivor
(AFC/B)
Pullet rearing
cost, (PUL$), $
5.745
5.834
5.901
5.958
6.005
Averacre Variable Costs / Breeder hen
survivor (AVC/B)
Feed, $
5.674
5.582
5.541
5.464
5.410
Prod, pay, $
3.900
3.988
4.092
3.939
4.044
Service &
supervision, $
.300
.300
.300
.300
.300
Averacre Total cost /
Breeder
hen survivor (ATC/B)
$
15.619
15.704
15.834
15.661
15.760
Salvacre adiustment /Breeder hen survivor
Egg salv., $
Hen salv., $
.131
1.075
.131
1.050
.131
1.021
.131
.981
. 131
.978
Adjusted
ATC/B, $
14.413
14.523
14.682
14.549
14.651
breeder mortality begins at 5% production and not at a
common age.

140
TABLE 6-6. Effect of feeding program on breeder hen average
cost budget through 40 weeks of production, calculated at
base prices and expressed as dollars per dozen hatching eggs
Feeding Program
+8% STD
-8%
-16%
-24%
Performance,, factors
Age, wk
64
65
66
67
68
Livability, %
*93
.93
.93
.93
.93
Feed,
kg/doz. H.E.
3.49
3.36
3.25
3,33
3.21
Hatching eggs,
doz/surv.
13.000
13.295
13.640
13,130
13,480
Average Fixed.... Costs
/DOZ. H.S. fAFC/El
Pullet
deprec., $
.442
.439
.435
.454
.445
Average Variable Costs / doz.
H.E,
fAVC/El
Feed, $
,436
.420
.406
.477
.401
Prod* pay, $
.300
.300
.300
.300
.300
Service &
supervision, $
.023
.023
,022
,023
.022
Average Total cost / doz. H.E.
(ATC/E)
$
1.201
1.181
1.161
1.193
1.169
Salvage adi ustment /, doz*,!LE
A.
Egg salv., $
Hen salv., $
.010
.083
.010
.079
.010
.075
.010
.075
.010
.073
Adjusted
ATC/E, $
1,109
1.092
1.076
1.108
1.087

141
TABLE 6-7. Average total cost of a dozen hatching eggs
produced to a common age by feeding program, calculated at
base prices and before salvage adjustment
Feeding Program
+8%
STD
-8%
-16%
-24%
Average Total
dozen hatching
Cost/
eggs
50 wk
1.395
1.371
1.386
1.508
1.508
55 wk
1.297
1.280
1.276
1.350
1.354
60 wk
1.233
1.216
1.206
1.257
1.253
65 wk
1.197
1.181
1.165
1.205
1.192
Proiected
70 wk
1.186
1.171
1.150
1.181
1.158
75 wk
1.185
1.172
1.148
1.171
1.138

142
TABLE 6-8. Live body weight (kg) by feeding program at
various transfer (laying house) ages and the relative
differences (%) among programs
Feeding Program
+8%
STD
-8%
-16%
-24%
Live weiaht.
(kg)
22 wk
2.48
2.33
2.11
1.89
1.75
24 wk
2.84
2.58
2.37
2.13
1.97
26 wk
3.09
2.85
2.61
2.33
2.18
Relative differences in
live weight from
std. m
22 wk
+6.0
-9.4
-18.9
-24.9
24 wk
+9.2
*
-8.1
-17.4
-23.6
26 Wk
+7.8
-8.4
-18.2
-23.5
Adiusted bird
densitv1
Potential
-7%
-
+7%
+14%
+21%
Adjusted base
bird density,
mVpullet
Ftz/pullet
.174
1.872
.163
1.750
.151
1.628
.140
1.505
.128
1.382
ATC/P
at 5% prod.
5.745
5.834
5.901
5.958
6.005
Adjusted
ATC/P
5.830
5.834
5.809
5.765
5.705
Potential adjustment in bird density relative to STD with a
margin of safety to maintain an equivalent bio-mass at
various transfer ages.

143
FIGURE 6-1. Average cost structure of a standars pullet
rearing program, at base prices.
s

a
s
15 1Q 15 20 25 30
AGE, CWIQ
FIGURE 6-2. Average cumulative feed cost for various pullet
feeding programs.

144
PRICE SITUATIONS
FIGURE 6-3, Sensitivity of pullet average total cost to
changes in component costs at 20, 25, and 30 weeks of age for
the STD feeding program (CHK=chick, PFD=pullet feed,
PPAY=grower pay, PMRT=pullet mortality, DENSITY=pullet housing
density).

DOLLARS / PULLET SURVIVOR
145
PRICE SITUATIONS
FIGURE 6-4. Sensitivity of pullet average total cost to
changes in component costs at 20, 25, and 30 weeks of age for
the -24% feeding program.

146
AGE AT 5* PRODUCTION, CWQ
FIGURE 6-5. Effect of a 20% change in component costs on
average total cost per pullet survivor at 5% production.
FIGURE 6-6. Average total cost of a dozen hatching eggs for
the STD and -24% feeding programs, with age.

147
PRICE SITUATIONS
FIGURE 6-7. Sensitivity of breeder hen average total cost to
changes in feed costs (BFD) or costs due to breeder hen
mortality (BMRT) at 40 weeks of production for the STD and
-24% feeding programs.

148
PRICE SITUATIONS
FIGURE 6-8. Sensitivity of breeder hen average total cost to
changes in pullet depreciation costs (PUL$) or costs due to
breeder hen mortality (BMRT) at 40 weeks of production for the
STD and -24% feeding programs.

149
AGE AT 5* PRODUCT ION., GWK}
FIGURE 6-9. Effect of changes in pullet housing density on
average total cost per pullet (ATC/P) at 5% production.
AGE, CWQ
FIGURE 6-10. Effect of adjusted pullet housing density on
average total cost of a dozen hatching eggs (ATC/E) on a STD
and -24% feeding program with age.

CHAPTER VII
SUMMARY AND CONCLUSIONS
In keeping with FSR/E methodology, this chapter is
written for the broiler breeder manager (client). It
presents an overview of the research findings presented in
this dissertation and makes practical recommendations in
broad terms so that breeder managers can understand, adjust
and utilize them within the context of their own particular
set of conditions.
A successful broiler breeder management program is one
that optimizes the use of feed, labor, capital and other
resources in the production of placeable chicks. To be
successful the breeder manager is required to make effective
decisions concerning the use of these resources during both
the rearing and production periods. This dissertation
examined four areas of breeder management that are important
to this decision making process. Specifically, the breeder
manager needs to: l) establish an effective body weight
monitoring and control program? 2) maximize the number of
placeable chicks per hen housed from a laying program? 3)
target the onset of sexual maturity; and 4) optimize returns
from pullet rearing and breeder hen laying programs.
150

151
Weighing Programs
Accurate and timely body weight estimates from an on-
farm weighing program enable the breeder manager to make
effective decisions concerning the proper quantity and
quality of feed to allocate to a flock. This body weight
information is an estimate of the flock's growth and
development response to environmental, genetic, health,
management and nutritional conditions. Variation in these
factors cause the decision making process to be a complex
task. Since body weight estimates are the basis for the
decision making process, any error in their estimates will
be reflected in the inefficient use of resources in the
rearing and production of a flock.
The overall objective of Chapter III was to establish
general guidelines for the development and implementation of
an appropriate weighing program. The study examined the
effect of scale type, sample units, sample size, sample
location, time of sampling, and complexity of procedures
used in estimating body weight, body weight gain and flock
uniformity.
It was found that a spring scale was as accurate as an
electronic scale in estimating average body weight, although
the printer feature of some electronic scales would probably
reduce transcription errors. Weighing birds individually
was found to be a better procedure than group weighing when
accurate estimates of flock uniformity are desired. A

Page
152
Missing
From
Original

153
Feeding Programs
In order for the breeder manager to maximize the number
of placeable chicks from a breeder rearing and laying
program, he must manage the feeding program so the average
body weight of a flock follows a growth curve established
for a particular strain. The overall objective of Chapter
IV was to evaluate the breeder's recommended growth curve by
comparing their standard growth curve with curves resulting
from severe feed restriction.
Proportional increases in the level of feed restriction
resulted in corresponding decreases in mean body weight for
the more restricted birds. The resulting growth curves for
the severely restricted birds paralleled the standard growth
curve, which was itself a good approximation of the
breeder's recommended growth curve. Feed restriction 16%
and 24% below standard permanently stunted the frame size
and reduced adult body weight of the breeders. Despite the
severity of restriction, there were no differences in either
pullet or breeder hen mortality, or in flock uniformity
among feed treatments. There appeared, however, to be a
trend towards increased mortality for the most restricted
birds.
Severe feed restriction significantly delayed flock
sexual maturity (age at 50% production) by ca. 1 wk for
every 8% restriction below standard. Average hen-day
production to the common age of 65 wk was significantly

154
lower for the -16% and -24% feed treatments. However, there
were corresponding and significant decreases in hen-day
production of double-yolked eggs among feed treatments. The
more restricted birds produced fewer double-yolked eggs and
thus increased their relative percentage of settable eggs.
When production was adjusted for double-yolked eggs and
mortality (hen-housed basis) there were no significant
differences between the standard and -24% feed treatments at
64 wk of age.
No differences were found in egg weights pooled over
the laying period due to feed treatment. Average egg weight
at the beginning of the production period was generally
higher for the more restricted birds which again contributed
to the difference in the number of settable eggs among feed
treatments. The more restricted birds produced eggs with
significantly better egg shell quality, as measured by
specific gravity, over the laying period. This difference
in shell quality was due to differences in egg weight,
although the -24% feed treatment had better shell quality
and equal egg weight relative to standard when averaged over
the laying period. In this study there were no differences
in fertility or hatchability of all eggs set due to feed
treatment.
Proportional differences in quantity of feed, protein
and energy consumption were a result of the feed allocation

155
program. The more restricted birds required less feed per
dozen hatching eggs than the standard.
The results indicate that feed restriction levels below
current recommendations can be used with broiler breeder
females without affecting fertility, hatchability, mortality
or average egg weight. The more severely restricted breeder
hen had a lighter mature body weight, smaller frame size and
consumed less feed without significantly reducing the number
of hatching eggs per hen-housed at 65 wk of age, when
compared to birds fed on a standard feeding program. The
implication of these results is that severe feed restriction
as a management technique can be utilized to maximize the
production of placeable chicks per hen housed while reducing
the cost of producing those chicks. This economic issue was
examined in Chapter VI.
Targeting Sexual Maturity
Under normal commercial pullet rearing conditions,
flock maturity occurs over a range of body weight X age
situations. This response is due to variation in
environmental, genetic, health, management and nutritional
factors. Furthermore, the nutritional requirements of the
maturing bird are increasing rapidly as the onset of egg
production occurs. Quantification of changes in the various
physical attributes associated with sexual maturity and
their use as feedback information for the breeder manager

156
during the pullet-layer transition period would make it
possible for the feeding and lighting programs to be more
properly adjusted to the changing needs of the flock at the
appropriate age.
The objective of Chapter V was to characterize how
these physical attributes associated with sexual maturity
would be affected by severe feed restriction as female
broiler breeders passed through the pullet-layer transition
period.
The various physical attributes measured were
classified as those increasing linearly with age, i.e.,
pubic spread, body and fat pad weight, comb development,
head score (comb and wattle appearance) and shank length,
and those that abruptly increased near sexual maturity,
i.e., total plasma lipid concentrations, and oviduct and
ovary weights. The bursa of Fabricius was a special case
that increased with age and body weight then regressed upon
sexual maturity.
The generalized effect of feed restriction on these
attributes was to delay their development without altering
their ultimate physiological values. The exceptions to this
finding were relative body weight and shank length after
maturity. The most severe feed restricted birds had reduced
skeletal size and body weight.
This study demonstrated that the breeder manager could
use measurements of the comb, pubic arch or a subjective

157
scoring of the head appearance as feedback information when
targeting sexual maturity in a flock. It is recommended
that a quantitative measurement of the comb be made,
recorded and graphed starting at ca. 20 wk of age by the
weighmaster.
Economic Analysis of Feeding Programs
Research findings reported in Chapter IV demonstrated
that the biological response to severe feed restriction
would be an equal number of hatching eggs at 65 wk of age on
a hen housed basis. However, the most severely restricted
birds required less feed to produce this equivalent quantity
of hatching eggs and the most severely restricted birds were
still at a significantly higher rate of production than
standard at 65 wk of age, e.g., ca. 63% vs. 52%.
The overall objective of Chapter VI was to conduct an
economic analysis of this biological response to feed
restriction in order that the economic optimum level of feed
restriction could be determined. Sensitivity analysis was
conducted to illustrate how the average cost of pullet
rearing or hatching egg production was affected by changes
in various fixed and variable costs.
When evaluated at 5% production, reduced feed expenses
due to severe feed restriction were not adequate to offset
the other increased pullet variable costs resulting from
delayed sexual maturity. Therefore, a more expensive pullet

158
(higher average cost) was capitalized at the start of the
breeder hen laying period, relative to standard. After 40
wk of production the average cost per breeder hen was still
higher for the most restricted feeding program. However,
when average total cost is expressed on the basis of a dozen
hatching eggs produced there was essentially no difference
between these feeding programs.
Projected average total cost (based on extrapolated
data) for the standard and most restricted feeding programs
beyond 65 wk of age suggests that the restricted birds would
have a lower average total cost than standard. This implies
that by extending the laying period beyond ca. 67 weeks of
age there will be an economic advantage for the severely
restricted birds.
Furthermore, severe feed restriction as a management
technique has the potential of significantly lowering the
average total cost of a dozen hatching eggs if pullet
housing density can be adjusted so that an equivalent bio
mass is maintained without any detrimental biological
affects to growth and production.
In conclusion, this dissertation demonstrated that a
breeder manager can increase returns to pullet growers,
hatching egg producers and the broiler integrator by: 1)
developing a body weight monitoring and control program that
assures the transmittal of accurate and timely information
from on-farm to the appropriate decision maker; 2) using

159
this information to control the growth and development of
pullets and breeder hens along a body weight curve that is
lower than presently recommended by industry; 3) assuring
that nutritional and lighting needs of the bird during the
pullet-layer transition period are met by recognizing the
onset of sexual maturity of the flock and adjusting the
feeding and lighting programs accordingly; 4) increasing the
housing density of the pullet flocks to a level that
maintains a normal pullet rearing bio-mass (assuming no
change in mortality will occur); and 5) extending the laying
period to ages where average total cost of a dozen hatching
eggs have reached a minimum level (assuming eggshell quality
can be maintained).
The importance of accurate and timely information from
the on-farm weighing program should not be underestimated
and procedures that address this issue should be
institutionalized within the breeder management program
before attempting to use severe feed restriction as a
management technique for optimizing economic returns from
pullet rearing and breeder hen laying programs.

REFERENCES
Abplanalp, H., and D. C. Lowry, 1975. Selection for
increased incidence of double-yolked eggs in White
Leghorn chickens. Poultry Sci. 54:17-24.
Abplanalp, H., D. C. Lowry, and J. H. Van Middelkoop, 1977.
Selection for increased incidence of double-yolked eggs
in White Leghorn chickens. Br. Poult. Sci. 18:585-
595.
Anthony, N. B., E. A. Dunnington, and P. B. Siegel, 1989.
Egg production and egg composition of parental lines
and Fi and F2 crosses of White Rock chickens selected
for 56-day body weight. Poultry Sci. 68:27-36.
Appleby, M. C., S. N. Maguire, and H. E. McRae, 1985.
Movement by domestic fowl in commercial flocks.
Poultry Sci. 64:48-50.
Arbor Acres, 1985. Broiler breeder male and female feeding
and management guide. Glastonbury, CT.
Avian Farms International, Ltd., 1989. Male and female
parent breeder management guide. Glastonbury, CT.
Bartov, I., S. Bornstein, Y. Lev, M. Pines, and J.
Rosenberg, 1988. Feed restriction in broiler breeder
pullets: skip-a-day versus skip-two-days. Poultry Sci.
67:809-813.
Bennett, C. D., and S. Leeson, 1989a. Water usage in
broiler breeders. Poultry Sci. 68:617-621.
Bennett, C. D., and S. Leeson, 1989b. Growth of broiler
breeder pullets with skip-a-day versus daily feeding.
Poultry Sci. 68:836-838.
Bilgili, S. F., and J. A. Renden, 1985. Relationship of
body fat to fertility in broiler breeder hens. Poultry
Sci. 64:1394-1396.
Blair, R., 1972. Feed restriction in breeding birds.
Feedstuffs, Minneap., 44(10):36-39.
160

161
Blair, R., M. M. MacCowan, and W. Bolton, 1976. Effects of
food regulation during the growing and laying stages on
the productivity of broiler breeders. Br. Poult. Sci.
17:215-223.
Blockhuis, H. J., J. W. Van der Haar, and J. M. M. Fuchs,
1988. Do weighing figures represent the flock average?
Poultry-Misset Int. 4(5):17-19.
Bornstein, S., S. Hurwitz, and Y. Lev, 1979. The amino acid
and energy requirements of broiler breeder hens.
Poultry Sci. 58:104-116.
Bornstein, S., and Y. Lev, 1982. The energy requirements of
broiler breeders during the pullet-layer transition
period. Poultry Sci. 61:755-765.
Bornstein, S., I. Plavnik, and Y. Lev, 1984. Body weight
and/or fatness as potential determinants of the onset
of egg production in broiler breeder hens. Br. Poult.
Sci. 25:323-341.
Brake, J., and G. R. Baughman, 1989. Comparison of lighting
regimens during growth on subsequent seasonal
reproductive performance of broiler breeders. Poultry
Sci. 68:79-85.
Brake, J., J. D. Garlich, and E. D. Peebles, 1985. Effect
of protein intake by broiler breeders during the
prebreeder transition period on subsequent reproductive
performance. Poultry Sci. 64:2335-2340.
Brody, T., Y. Eitan, M. Soller, I. Nir, and Z. Nitsan, 1980.
Compensatory growth and sexual maturity in broiler
females reared under severe food restriction from day
of hatching. Br. Poult. Sci. 21:437-446.
Brody, T. B., P. B. Siegel, and J. A. Cherry, 1984. Age,
body weight and body composition requirements for the
onset of sexual maturity of dwarf and normal chickens.
Br. Poult. Sci. 25:245-252.
Brown, R. H., 1989. Poultry industry optimistic as chicken
tops beef. Feedstuffs 61(5):1,39-40.
Bullock, D. W., T. R. Morris, and S. Fox, 1963. Protein and
energy restriction for replacement pullets. Br. Poult.
Sci. 4:227-237.
Cave, N. A., 1984a. Stimulation lighting of meat-type
pullets. Poultry Sci. 63:1101-1104.

162
Cave, N. A., 1984b. Effects of a high-protein diet fed
prior to the onset of lay on performance of broiler
breeder pullets. Poultry Sci. 63:1823-1827.
Chaney, L. W., and H. L. Fuller, 1975. The relation of
obesity to egg production in broiler breeders. Poultry
Sci. 54:200-208.
Christmas, R. B., and R. H. Harms, 1982. Incidence of
double yolked eggs in the initial stages of lay as
affected by strain and season of the year. Poultry
Sci. 61:1290-1292.
Conrad, R. M., and D. C. Warren, 1940. The production of
double yolked eggs in the fowl. Poultry Sci. 19:9-17.
Cook, R. E., 1988. Poultry research programs in the future.
Poultry Sci. 67:890-896.
Costa, M. S., 1981. Fundamental principals of broiler
breeders nutrition and the design of feeding
programmes. World/s Poult. Sci. J. 37:177-192.
Craig, J. V., and A. M. Guhl, 1969. Territorial behavior
and social interactions of pullets kept in large
flocks. Poultry Sci. 48:1622-1628.
Dobbs, J. D., and D. C. Lowry, 1976. Yolk deposition in
double yolked eggs in a line of chickens selected for
simultaneous multiple ovulations. Poultry Sci.
55:2029.
Feighner, S. D., E.F. Godowsky, and B. M. Miller, 1986.
Portable microcomputer-based weighing systems:
Applications in poultry science. Poultry Sci. 65:868-
873.
Folch, J., M. Lees, and G. H. Sloan-Stanley, 1957. A simple
method for the isolation and purification of total
lipids from animal tissue. J. Biol. Chem. 226:497-
509.
Fuller, H. L., D. K. Potter, and W. Kirkland, 1969. Effect
of delayed maturity and carcass fat on reproductive
performance of broiler breeder pullets. Poultry Sci.
48:801-809.
Fuquay, J. I., and J. A. Renden, 1980. Reproductive
performance of broiler breeders maintained in cages or
on floors through 59 weeks of age. Poultry Sci.
59:2525-2531.

163
Gomez, K. A., and A. A. Gomez, 1984. Statistical Procedures
for Agricultural Research. John Wiley and Sons, Inc.,
New York, NY.
Gvaryahu, G., D. L. Cunningham, and A. Van Tienhoven, 1989.
Filial imprinting, environmental enrichment, and music
application effects on behavior and performance of meat
strain chicks. Poultry Sci. 68:211-217.
Gvaryahu, G., N. Snapir, and B. Robinzon, 1987. Research
note: Application of the filial imprinting phenomenon
to broiler chicks at a commercial farm. Poultry Sci.
66:1564-1566.
Harms, R. H., 1984. The influence of feeding program on
peak production and avoiding sudden declines in
production with broiler breeders. Poultry Sci.
63:1667-1668.
Harms, R. H., S. M. Bootwalla, and H. R. Wilson, 1984a.
Performance of broiler breeder hens on wire and litter
floors. Poultry Sci. 63:1003-1007.
Harms, R. H., F. B. Mather, C. R. Douglas, and S. M. Free,
1984b. A method for weighing pullets during the
growing period. Poultry Sci. 63:443-446.
Harms, R. H., R. A. Voitle, and H. R. Wilson, 1979.
Performance of broiler breeder pullets grown on various
grower programs. Nutr. Rept. Int. 20(4):561-566.
Harms, R. H., and H. R. Wilson, 1980. Protein and sulfur
amino acid requirements of broiler breeder hens.
Poultry Sci. 59:470-472.
Hocking, P. M., A. B. Gilbert, M. Walker, and D. Waddington,
1987. Ovarian follicular structure of White Leghorns
fed ad libitum and dwarf and normal broiler breeders
fed ad libitum or restricted to point of lay. Br.
Poult. Sci. 28:493-506.
Hocking, P. M., D. Waddington, M. A. Walker, and A. B.
Gilbert, 1989. Control of the development of the
ovarian follicular hierarchy in broiler breeder pullets
by food restriction during rearing. Br. Poult. Sci.
30:161-174.
Hubbard Farms, Inc., 1988-89. Hubbard breeder pullet
management guide. Walpole, NH.

164
Ingram, D. R., and H. R. Wilson, 1987. Ad libitum feeding
of broiler breeders prior to peak egg production.
Nutr. Rept. Int. 36:839-845.
Ingram, D. R., and H. R. Wilson, and F. B. Mather, 1988.
Influence of lighting program and rate of body weight
gain on sexual maturity and performance of broiler
breeders. Nutr. Rept. Int. 38:29-35.
Jaap, R. G., 1955. Sampling body weight of growing
chickens. Poultry Sci. 34:396-397.
Katanbaf, M. N., E. A. Dunnington, and P. B. Siegel, 1989a.
Restricted feeding in early and late-feathering
chickens. 1. Growth and physiological response.
Poultry Sci. 68:344-351.
Katanbaf, M. N., E. A. Dunnington, and P. B. Siegel, 1989b.
Restricted feeding in early and late-feathering
chickens. 2. Reproductive response. Poultry Sci.
68:352-358.
Katanbaf, M. N., E. A. Dunnington, and P. B. Siegel, 1989c.
Restricted feeding in early and late-feathering
chickens. 3. Organ size and carcass composition.
Poultry Sci. 68:359-368.
Lavie, D., 1988. Imprinting offers possibilities for
broiler chicks. Poultry-Misset Int. 4(5):17-19.
Lee, P. J. W., A. L. Gulliver, and T. R. Morris, 1971. A
quantitative analysis of the literature concerning the
restricted feeding of growing pullets. Br. Poult. Sci.
12:413-437.
Leeson, S., and J. D. Summers, 1983. Consequence of
increased feed allowance for growing broiler breeder
pullets as a means of stimulating early maturity.
Poultry Sci. 62:6-11.
Leeson, S., and J. D. Summers, 1984. Influence of
nutritional modification on skeletal size of Leghorn
and broiler breeder pullets. Poultry Sci. 63:1222-
1228.
Leeson, S., and J. D. Summers, 1985. Effect of caged versus
floor rearing and skip-a-day versus every-day feed
restriction on performance of dwarf broiler breeders
and their offspring. Poultry Sci. 64:1742-1749.

16E
Lilburn, M. S., K. Ngiam-Rilling, and J. H. Smith, 1987.
Relationship between dietary protein, dietary energy,
rearing environment, and nutrient utilization by
broiler breeder pullets. Poultry Sci. 66:1111-1118.
Lilburn, M. S., K. Rilling, F. Mack, E. 0. Mills, and J. H.
Smith, 1986. Growth and development of broiler
breeders. 1. Effect of early plane of nutrition and
growth rate. Poultry Sci. 65:1070-1075.
Lott, B. D., F. N. Reece, and J. L. McNaughton, 1982. An
automated weighing system for use in poultry research.
Poultry Sci. 61:236-238.
Lowry, D. C., and H. Abplanalp, 1967. Selection for an
increase in multiple ovulation in the chicken.
Genetics 56:573-574.
Lowry, D. C., J. C. Dobbs, and H. Abplanalp, 1979. Yolk
deposition in eggs of a line selected for simultaneous
multiple ovulation. Poultry Sci. 58:498-501.
Luther, L. W., W. W. Abbott, and J. R. Couch, 1976. Low
lysine, low protein, and skip-a-day restriction of
summer and winter reared broiler breeder pullets.
Poultry Sci. 55:2240-2247.
May, J. D., S. L. Branton, J. W. Deaton, and J. D. Simmons,
1988. Effect of environmental temperature and feeding
regimen on quantity of digestive tract content of
broilers. Poultry Sci. 67:64-71.
McDaniel, G. R., 1974. The production of broiler hatching
eggs in cages. Poultry Sci. 53:1954.
McDaniel, G. R., 1983. Factors affecting broiler breeder
performance. 5. Effects of preproduction feeding
regimens on reproductive performance. Poultry Sci.
62:1949-1953.
McDaniel, G. R., J. Brake, and R. D. Bushong, 1981a.
Factors affecting broiler breeder performance. 1.
Relationship of daily feed intake level to reproductive
performance of pullets. Poultry Sci. 60:307-312.
McDaniel, G. R., J. Brake, and M. K. Eckman, 1981b. Factors
affecting broiler breeder performance. 4. The
interrelationship of some reproductive traits.
Sci. 60:1792-1797.
Poultry

166
Meltzer, A., and D. Landsberg, 1988. The modern approach to
weighing poultry. Int. Hatchery Practice 2(6):27-29.
Mench, J. A., and M. M. Shea, 1988. Effects of feed
restriction and tryptophan on the behavior of broiler
breeders. In: Proc. Maryland Nutr. Conf., Poultry Sci
Dept., Univ. of Maryland, College Park, MD.
Montgomery, D. C., 1984. Design and Analysis of
Experiments. John Wiley and Sons, Inc., New York, NY.
Morris, T. R., 1967. Light requirements of the fowl. pp.
15-29 In: Environmental Control in Poultry Production.
T. C. Carter, ed. Oliver and Boyd, Edinburgh,
Scotland.
Moultry, F., 1983. Feeding and lighting trials with broiler
breeders a progress report. In: Proc. Arkansas Nutr.
Conf., Dept, of Animal Sciences, Univ. of Arkansas,
Fayetteville, AR.
Murphy, L. B., and A. P. Preston, 1988. Food availability
and the feeding and drinking behavior of broiler
chickens grown commercially. Br. Poult. Sci. 29:273-
283.
National Research Council, 1984. Nutrient Requirements of
Poultry. 8th ed. National Academy Press, Washington,
DC.
Newberry, R. C., J. R. Hunt, and E. E. Gardiner, 1985.
Behaviour of roaster chickens towards an automatic
weighing perch. Br. Poult. Sci. 26:229-237.
North, M. 0., 1984. Commercial Chicken Production Manual.
Third Edition. Avi Publ. Co., Inc., Westport, CT.
Ogunji, P. A., R. N. Brewer, D. A. Roland, Sr., and D.
Caldwell, 1983. Effect of sodium chloride, protein,
and strain difference upon water consumption and fecal
moisture of broiler breeder males. Poultry Sci.
62:2497-2500.
Oruwari, B. M., and T. Brody, 1988. Roles of age, body
weight and composition in the initiation of sexual
maturation of Japanese quail (Coturnix coturnix
japnica). Br. Poult. Sci. 29:481-488.
Patterson, P. H., M. L. Sunde, and J. L. Pimentel, 1989.
Water consumption and fecal moisture of laying hens fed
wheat middlings and corn-soybean-alfalfa meal diets.
Poultry Sci. 68:830-833.

16
Payne, C. G., 1975. Day-length during rearing and the
subsequent egg production of meat-strain pullets. Br.
Poult. Sci. 16:559-563.
Pearson, R. A., and K. M. Herron, 1980. Feeding standards
during lay and reproductive performance of broiler
breeders. Br. Poult. Sci. 21:171-181.
Pearson, R. A., and K. M. Herron, 1981. Effects of energy
and protein allowances during lay on the reproductive
performance of broiler breeder hens. Br. Poult. Sci.
22:227-239.
Pearson, R. A., and K. M. Herron, 1982a. Effects of
maternal energy and protein intakes on the incidence of
malformations and malpositions of the embryo and time
of death during incubation. Br. Poult. Sci. 23:71-77.
Pearson, R. A., and K. M. Herron, 1982b. Relationship
between energy and protein intakes and laying
characteristics in individually-caged broiler breeder
hens. Br. Poult. Sci. 23:145-159.
Perry, G. C., D. R. Charles, P. J. Day, J. R. Hartland, and
P. G. Spencer, 1971. Egg-laying behavior in a broiler
parent flock. World/s Poult. Sci. J. 27(abstr.):162.
Peterson Farms, 1988. Broiler breeders management guide.
Decatur, AR.
Petitte, J. N., R. O. Hawes, and R. W. Gerry, 1981. Control
of flock uniformity of broiler breeder pullets through
segregation according to body weight. Poultry Sci.
60:2395-2400.
Petitte, J. N., R. 0. Hawes, and R. W. Gerry, 1982. The
influence of flock uniformity on the reproductive
performance of broiler breeder hens housed in cages and
floor pens. Poultry Sci. 61:2166-2171.
Petitte, J. N., R. O. Hawes, and R. W. Gerry, 1983. The
influence of cage versus floor pen management of
broiler breeder hens on subsequent performance of cage
reared broilers. Poultry Sci. 62:1241-1246.
Proudfoot, F. G., H. W. Huan, and K. B. McRae, 1980. The
effect of several different photoperiods on the
performance of meat-parent genotypes. Can. J. Anim.
Sci. 60:21-31.

16
Proudfoot, F. G., H. W. Huan, and K. B. McRae, 1984.
Effects of photoperiod, light intensity and feed
restriction on the performance of dwarf and normal
maternal poultry meat genotypes. Can. J. Anim. Sci.
64:759-768.
Proudfoot, F. G., H. W. Huan, and K. B. McRae, 1985.
Effects of age at photoperiod change and dietary
protein on performances of four dwarf maternal meat
parent genotypes and their broiler chick progeny. Can.
J. Anim. Sci. 65:113-124.
Proudfoot, F. G., and W. F. Lamoreux, 1973. The bio-
economic effect of nutrient intake restrictions during
the rearing period and post "peak" egg production feed
restriction on four commercial meat-type parental
genotypes. Poultry Sci. 52:1269-1282.
Pym, R. A., and J. F. Dillon, 1969. The effect of some
feeding and laying feeding regimes on the initial
reproductive performance of broiler type pullets.
Proc. Australia Poult. Sci. Conv., 167-178.
Pym, R. A., and J. F. Dillon, 1974. Restricted food intake
and reproductive performance of broiler breeder
pullets. Br. Poult. Sci. 15:245-259.
Rishell, W. A., (NA). Trade-off values affect the genetic
objectives. Arbor Acres Review 23(1):1-4.
Robbins, K. R., S. F. Chin, G. C. McGhee, and K. D.
Roberson, 1988. Effects of ad libitum versus
restricted feeding on body composition and egg
production of broiler breeders. Poultry Sci. 67:1001-
1007.
Romanoff, A. L., and A. J. Romanoff, 1949. The Avian Egg.
John Wiley and Sons, Inc., New York, NY.
Ross Poultry Breeders, Inc., 1986. Ross breeders Broiler
parent stock management manual 208. Elkmont, AL.
SAS Institute Inc., 1985. SAS/STAT guide for personal
computers, version 6 edition. Cary, NC.
SAS Institute Inc., 1987. SAS/Graph guide for personal
computers, version 6 edition. Cary, NC.
Sharp, P. J., G. Beuving, and J. H. Van Middlekoop, 1976.
Plasma lutenizing hormone and ovarian structure in
multiple ovulating hens. Proc. 5th Europ. Poultry
Conf., Malta 11:1259-1264.

169
Soller, M., T. Brody, Y. Eitan, T. Angursky, and C. Wexler,
1984a. Minimum weight for onset of maturity in female
chickens: Heritability and phenotypic and genetic
correlations with early growth rate. Poultry Sci.
63:2103-2113.
Soller, M., Y. Eitan, and T. Brody, 1984b. Effect of diet
and early feed restriction on the minimum weight
requirement for onset of sexual maturity in White Rock
broiler breeders. Poultry Sci. 63:1255-1261.
Spratt, R. S., and S. Leeson, 1987. Broiler breeder
performance in response to diet protein and energy.
Poultry Sci. 66:683-693.
Strain, J. H., and A. W. Nordskog, 1962. Genetic aspects of
the profit equation in a broiler enterprise. Poultry
Sci. 41:1892-1902.
Stutz, M. W., D. E. Mayer, and J. P. Glatzhofer, 1984. An
automated weighing and analysis system for growth and
feed efficiency studies. Poultry Sci. 63:49-54.
Summers, J. D., W. F. Pepper, S. J. Slinger, and J. D.
McConachie, 1967. Feeding meat type pullets and
breeders. Poultry Sci. 46:1158-1164.
Turner, M. J. B., P. Gurney, and C. G. Belyavin, 1983.
Automatic weighing of layer-replacement pullets housed
on litter or in cages. Br. Poult. Sci. 24:33-45.
Van Krey, H. P., and W. D. Weaver, Jr., 1988. Effects of
feeder space on body weight uniformity of broiler
breeder pullets during an alternate day feeding
program. Poultry Sci. 67:996-1000.
Vergara, P., M. Jimenez, C. Ferrando, E. Fernandez, and E.
Gonalons, 1989. Age influence on digestive transit
time of particulate and soluble markers in broiler
chickens. Poultry Sci. 68:185-189.
Waldroup, P. W., and K. R. Hazen, 1976. A comparison of the
daily energy needs of the normal and dwarf broiler
breeder hen. Poultry Sci. 55:1383-1393.
Waldroup, P. W., K. R. Hazen, W. D. Bussell, and Z. B.
Johnson, 1976. Studies on the daily protein and amino
acid needs of broiler breeder hens. Poultry Sci.
55:2342-2347.

170
Watson, N. A., 1975. Reproductve activity of broiler hens
subjected to restricted feeding during rearing. Br.
Poult. Sci. 16:259-262.
Whitehead, C. C., K. M. Herron, and D. Waddington, 1987.
Reproductive performance of dwarf broiler breeders
given different allowances of food during the rearing
and breeding periods and two lighting patterns. Br.
Poult. Sci. 28:415-427.
Williams, J. B., and P. J. Sharp, 1978. Ovarian morphology
and rates of ovarian follicular development in laying
broiler breeders and commercial egg-producing hens.
Br. Poult. Sci. 19:387-395.
Wilson, H. R., and R. H. Harms, 1984. Evaluation of
nutrient specifications for broiler breeders. Poultry
Sci. 63:1400-1406.
Wilson, H. R., and R. H. Harms, 1986. Performance of
broiler breeders as affected by body weight during the
breeding season. Poultry Sci. 65:1052-1057.
Wilson, J. L, and N. Dale, 1989. Effect of 20 week body
weight on subsequent performance of broiler breeder
hens. Poultry Sci. 68(Sup. 1):159.
Yu, J. Y. L., and R. R. Marquardt, 1974. Hyperplasia and
hypertrophy of the chicken (Gallus domesticus) oviduct
during a reproductive cycle. Poultry Sci. 53Roge
lios.
Zelenka, D. J., J. A. Cherry, I. Nir, and P. B. Siegel,
1984. Body weight and composition of Japanese quail
(Coturnix coturnix japnica) at sexual maturity.
Growth 48:16-28.
Zelenka, D. J., D. E. Jones, E. A. Dunnington, and P. B.
Siegel, 1987. Selection for body weight at eight weeks
of age. 18. Comparisons between mature and immature
pullets at the same live weight and age. Poultry Sci.
66:41-46.
Zelenka, D. J., P. B. Siegel, and H. P. Van Krey, 1986.
Ovum formation and multiple ovulation in lines of White
Plymouth Rocks and their crosses. Br. Poult. Sci.
27:409-414.

BIOGRAPHICAL SKETCH
The author, Thomas Richard Fattori, was born on
December 24, 1950, in Teaneck, New Jersey. He graduated
from Don Bosco Preparatory High School in 1969. Thomas
studied animal biology at Washington State University until
he received a Bachelor of Science in Animal Science degree
in 1973. He then spent 10 years working in the area of
international agricultural development in Francophone Africa
and Europe. His cross-cultural experiences included
logistic and market surveys, feasibility analysis and
project planning. He is fluent in French and has traveled
widely throughout the world.
Thomas received a Master of Science in Poultry Science
from the University of Florida in 1987. His major field was
poultry management with a minor in farming systems.
Thomas is presently completing a Ph.D. degree in animal
science with a major in poultry management and a double
minor in farming systems and food and resource economics.
He is working under the direction of Dr. H. R. Wilson
(physiologist) and Dr. P. E. Hildebrand (production
economist). His duties include being a farming systems
171

172
research assistant to his coadvisors while conducting
dissertation research.
Thomas is a member of the Poultry Science Association,
World's Poultry Science Association, Gamma Sigma Delta and
Phi Kappa Phi. He was the recipient of the Ruby V. Voitle
Award for Outstanding Graduate Student in 1987-88 and the
Maurice Stein Fellowship for Academic Achievement in Poultry
Economics in 1988. Tom was selected in 1988 as the graduate
student representative on the search committee for a Vice
President of Agricultural Affairs at the University of
Florida. Tom was the recipient of a Certificate of
Excellence in recognition of his presentation of a research
paper at the national Poultry Science Association meetings
in July, 1989.
Thomas married the former Maisha Verwilghen in
Kinshasa, Zaire, in 1980. They presently have two sons,
Jonathan and Benjamin, who are eight and six years old,
respectively.
His main area of interest is in technology assessment
from a bio-economic perspective and his career goal is to be
a member of a multidisciplinary research team that is
responsible for the coordination of financial, logistic,
research and diffusion strategies for a poultry enterprise
or institution.



77
is illustrated in Figure 4-6. Generally, the -24% egg
weights were proportionately lighter and in parallel with
STD as the flock aged. By 58 wk of age egg weights
converged and no significant difference in egg weight could
be detected (Table 4-6) even though the body weights were
significantly different at this time. No differences were
found in egg weights pooled over the production cycle. The
normally arc-shaped egg weight curve appeared to flatten for
all treatments from wk 38 through 52, which corresponded to
the period of highest ambient temperatures.
Measurements on specific gravity exhibited similar but
reversed trends from egg weight. The -24% treatment had
proportionately better shell quality as specific gravity
values paralleled STD. No difference between treatments on
specific gravity or egg weight measurements could be
detected during early or late stages of the production
cycle.
The correlation coefficients between egg weight and
specific gravity are presented in Table 4-6, with their
corresponding probabilities of significance. Correlations
within treatments and pooled over the production cycle
revealed that all feed treatments had similar and highly
significant negative correlations. Correlations among
treatments characterize the age effect on these two
parameters. The positive correlation at 30 wk of age is due
to the delay in the start of the production cycle for the


LIST OF TABLES
Table Page
3-1 Effect of feeding time (ERL vs. LTE) and time
of day on non-laying broiler breeder female
mean body weight and weight change (Exp. 1) 56
3-2 Effect of scale type (ELC vs. SPR) and sample
units (IND vs. GRP), on mean adult breeder hen
and breeder pullet body weight and uniformity
(SD) (Exp. 2) 57
3-3 Effect of sample location (FDD vs. END) and
sample type (PND vs. FXD) on mean straight-run
broiler body weight and uniformity (SD),
(Exp. 3) 58
3-4 Effect of sample location (FDD vs. END) at
various ages and by sample type (PND vs. FXD)
on mean pullet body weight and uniformity (SD),
(Exp. 3) 59
3-5 Effect of sample location (FDD vs. END) at
various ages and by sample type (PND vs FXD) on
mean breeder hen body weight and uniformity (SD),
(Exp. 3) 60
3-6 Effect of sample location (FDD vs. END) on mean
breeder hen and pullet body weight gain (Exp. 3). 61
3-7 Classification of suspect outliers as true
outliers by testing mean body weight with an
outlier interval (+ 3*SD) for broilers, pullets
and breeder hens (Exp. 3) 62
3-8 Effect of sample size on mean and variance of
body weight for broilers, pullets and breeder
hens 63
4-1 Composition, calculated nutrient content and age
used for the starter and grower diets 80
4-2 Daily nutrient intake of broiler breeders after
20 weeks of age 81
vi


FAT PAD
o
108
150 -
o= + 8 x 0 = s T D & = 8 % FIGURE 5-2. Effect of feed treatment on fat pad weight (g)
with respect to age (wk) and body weight (g).
28


134
production (ATC/E), essentially no cost differences among
feeding programs were evident by ca. 67 wk of age.
Production estimates projected beyond this age indicated
that the most severe feed restriction program resulted in
decreasing ATC through 78 wk of age.
Severe feed restriction as a management technique has
the potential of lowering the ATC/E, if the assumption that
increasing pullet housing density to an equivalent bio-mass
with standard densities will not have any detrimental effect
to growth and production holds true.


27
protein levels improved liver metabolism and function and/or
strengthened the infundibulum which could aid in the
capturing of ovulated yolks. This suggests that as the bird
passes through the pullet-layer transition period a
quantitative change in protein required for the development
of the reproductive tract is separate from the need for body
weight gain (Li1burn, 1987).
Energy
A study conducted by Brake et al. (1985), investigating
protein, energy and their interactions revealed that
significant protein X energy interactions occurred for egg
weight during wk 25 through 44, but not overall. Wo
differences in the main effect of protein level on egg
specific gravity or fertility were found.
Ingram and Wilson (1987) reported that hens fed ad
libitum for various lengths of time during the pullet-layer
transition period laid at higher rates than their more
restricted counterparts through ca. 43 wk of age. However,
after wk 44 the hens full fed for 6 to 8 wk laid at a
significantly lower rate than the more restricted birds.
This was perhaps due to excessive levels of body weight gain
past 40 wk which led to body weights in excess of 4.0 Kg by
this time.
Robbins et al. (1988) reported that ad libitum feeding
during the pullet-layer transition resulted in more eggs,
but the effect was not significant. Egg weight and specific


TABLE 5-1. Continued
Age
Trait
BURSA
SHANK
ARCH
COMB
HEAD
Cwk)
r
Prob
r
Prob.
r
Prob.
r
Prob.
r
Prob.
20\22
BWT
.46
.04
.52
.02
.69
*
.43
.06
.60
.01
FTPD
.53
.02
.30
.20
.62
*
.49
.03
.63
*
LIPID
.24
.32
.44
.05
.23
.32
.12
.61
.27
.25
OVARY
.28
.25
.24
.31
.51
.02
.06
.81
.31
.18
OVID
.56
.01
.10
.67
.59
.01
.43
.06
.40
.08
BURSA
*
.99
.32
.18
.27
.25
.46
.04
SHANK
.26
.27
.54
.01
.10
.69
-.04
.87
ARCH
.51
.02
.48
.03
.47
.04
.44
.05
COMB
.52
.02
.35
.13
.62
*
.84
*
HEAD
.54
.01
.31
.18
.64
*
CO
CO
*
24\26
BWT
.33
.16
.48
.03
.64
*
.65
*
.68
*
FTPD
.33
.16
.18
.44
.64
*
.58
.01
.62
*
LIPID
.33
.16
.25
.28
.48
.03
.51
.02
.54
.01
OVARY
-.29
.22
-.17
.48
.53
.02
.22
.36
.40
.08
OVID
-.29
.22
*
.98
.72
*
.54
.01
.69
*
BURSA
.32
.17
.28
.23
-.17
.48
-.19
.44
SHANK
-.01
.96
.17
.48
.08
.73
.19
.42
ARCH
.12
.61
.27
.26
.40
.08
.53
.02
COMB
.03
.91
.43
.06
.82
*
.87
*
HEAD
.07
.78
.60
.01
.64
*
in
CO
*
28\ALL
BWT
.14
.18
.50
*
.73
*
.73
*
.75
*
FTPD
.13
.19
.30
*
.67
*
.68
*
.66
*
LIPID
-.11
.28
.45
*
.64
*
.58
*
.51
*
OVARY
-.36
*
-.09
.38
.61
*
.46
*
.46
*
OVID
-.29
*
.06
.54
.81
*
.68
*
.66
*
BURSA
.09
.40
-.16
.12
-.17
.10
-.07
.52
SHANK
.04
.86
.25
.01
.21
.04
.27
.01
ARCH
- .43
.06
.47
.04
.75
*
.76
*
COMB
-.31
.19
.44
.05
.65
*
.87
*
HEAD
-.26
.27
.48
.03
.78
*
.79
*
102


81
TABLE 4-2. Daily nutrient intake of broiler breeders after
20 weeks of age
Nutrient
Daily intake / bird
Protein, g
20.6
Sulfur amino acids, mg
754
Methionine, mg
400
Lysine, mg
938
Arginine, mg
1379
Tryptophan, mg
256
Calcium, g
4.07
Phosphorous, mg1
683
Sodium, mg
170
Vitamins2

Energy3

Expressed as total phosphorus.
2Levels of vitamins and trace minerals in finished feed met
minimum daily intake suggested by National Research Council
(1984) .
3Diets were formulated for feed intake of 109 to 204 g/bird
per day. Examples of energy intake are 301, 398, 495, and
636 kcal per day for diets formulated for 109, 137, 164, and
204 g/bird per day feed consumed.


121
by projecting a linear increase in mortality at the
estimated base rate of .2% per wk starting from 1 wk of age
and resulting in 4, 5, and 6% cumulative mortality at 20, 25
and 30 wk of age, respectively. Similarly, a base rate for
breeder hen mortality and culling (BMRT) was determined by
linearly increasing mortality at the rate of .175% per wk
from the appropriate age at 5% production to 7, 7.9 and 8.7%
cumulative mortality after 40, 45, and 50 wk of production,
respectively.
Sensitivity Analysis and Prices
Sensitivity analysis indicates change in average total
costs for pullet rearing or breeder hen enterprises in
response to a 20% change in a component cost, with all other
costs held constant. The base price situation used in this
analysis was consistent with commercial prices found in the
Southeastern United States in 1988. Tables 6-1 and 6-2 list
the base price estimates and the corresponding +20%
adjustment made to the base prices.
Fixed Costs
Pullet rearing. Base female and male chick costs (CHK)
were estimated to be $1,72 and $2.75 respectively (Table 6-
1). Initial quantity purchased was adjusted for expected
mortality which allowed for a 9 to 1 female to male ratio of
survivors at 25 wk of age.
Breeder hens. Average total cost of a pullet survivor
reared to 5% production for a particular feed treatment


5
breeder rearing and laying program, 3) target sexual
maturity, and 4) optimize economic returns from pullet
rearing and breeder hen laying programs.
Hypotheses
Hyp.oth_e,s,is_l
If procedures for the on-farm weighing of broilers,
broiler breeder pullets and breeder hens can be optimized
with respect to the total time (cost) required to conduct
the weighing program, then monetary returns to the growers,
breeders and integrator will increase. Increased returns
will result from more efficient use of labor and feed
resources, as well as increased breeder reproductive
performance.
Hypqthes is__2
If the appropriate broiler breeder body weight growth
curve resulting from a level of feed restriction can be
identified, then reproductive performance (placeable chicks)
of a housed flock can be maximized.
Hy pot he s i.s_3
If changes in the physical characteristics of a breeder
hen that signal the onset of sexual maturity as she passes
through the pullet-layer transition period can be identified
for various degrees of severe feed restriction, then these


39
development of ovarian follicles. The inheritance of the
tendancy to produce double-yolked eggs through genetic
selection has been demonstrated by Lowry and Abplanalp
(1967), Abplanalp and Lowry (1975), and Abplanalp et al.
(1977). Williams and Sharp (1978) reported that as laying
breeder hens become older, the initial decrease in egg
production and the increase in egg size is a reflection of
the way in which yellow yolk accumulates in a smaller number
of follicles which grow to a larger size before they
ovulate. Furthermore, the incidence of double yolked eggs
is normally reduced to low levels as the breeder hen ages.
Christmas and Harms (1982) summarized data on 12
strains of egg-type hens to determine the influence of
strain and season of the year on the incidence of double-
yolked eggs in the initial stages of lay. They found a
significant strain effect on the incidence of double-yolked
eggs at the onset of lay. The incidence ranged from 1.1 to
3.5% hen-day production. Spring and summer-housed laying
hens produced a greater number of double-yolked eggs than
did those housed in the late fall or winter months. The
incidence of double-yolked eggs and age at 50% production
were significantly correlated, however, it was thought to be
a season rather than a within-strain maturity effect.
Feed restriction during the rearing period has been
shown to limit the production of yellow follicles and the
incidence of double ovulations, leading to an increase in


20
£ullet_.,.Rearipg, Period
Mortality
Lee et al. (1971) cited 63 experiments out of 80 where
higher mortality was associated with feed restriction during
the rearing period, and most of the increase was due to
coccidiosis. since restricted birds are known to increase
litter intake (Harms etal., 1984a) and water intake
(Patterson, 1989) it is not surprising that levels of
mortality due to coccidiosis would be higher* However, Pym
and Dillon (1974) noted that when coccidiosis is well
managed, restriction levels of 60 to 80% of ad libitum
appeared not to have a detrimental effect on rearing
mortality. These researchers also showed that heat stress
mortality for birds fed ad libitum was significantly higher
than for restricted fed birds. They observed that during
the heat stress period the more severely restricted birds
moved around more freely and drank much more water than
birds fed ad libitum.
Mortality levels for pullets reared on 12, 14, 16 and
18% protein diets were not significantly different for
broiler breeders (summers et al., 1967). This was in
contrast to findings by Bullock et al. (1963) and Blair,
(1972) who found increased mortality among pullets fed even
lower protein (10%) grower diets.


129
20% increase in pullet DNSTY offset the cost of delayed
pullet maturity. Under the scenario of increased pullet
DNSTY the pullet grower benefits from 3 wk of additional
revenue, the source of which was from PFD savings from the
-24% feed program.
Breeder Hen Period
Comparison of the breeder hen cost budgets for the STD
and -24% feeding programs (Table 6-5), shows a $.056 lower
ATC/B before salvage adjustments for the STD program. The
$.172 savings in BFD cost offset the added pullet rearing
(PUL$) cost ($.171) for the -24% program. The $.056
difference resulted from higher producer payments (BPAY) for
the production of hatching eggs. However, the $.056
difference increased to $.128 when salvage adjustments were
made, reflecting the heavier average body weight of breeder
hens on the STD program after 40 wk of production.
After 40 wk of production ATC/B for the STD and -24%
programs were $15,704 and $15,760, respectively, before
salvage adjustments were made. Generally, the ATC/B can be
partitioned into 40% for PUL$, 34% for BFD, 24% for BPAY and
2% for BSRV. Salvage adjustments (Table 6-5) represented a
potential recuperation of ca. 7-8% of ATC/B.
The combined average cost of rearing a pullet to 5%
production (PUI*$) and breeder feed (BFD) cost accounted for
74% of ATC/B. Mortality in the breeder house increased
total cost by $1.10 through lost feed and higher pullet


58
TABLE 3-3. Effect of sample location (FDD vs. END) and
sample type (PND vs. FXD) on mean straight-run broiler body
weight and uniformity (SD),(Exp. 3)
Age Trial Pop. Sample Location
(d)
No.
Size
Type
FDD
END
Sig.
Pooled
40
1
24,500
PND
N,
no.
70
78
mean, g
1683
1663
NS1
SD,
9
198
199
NS2
PND
N ,
no.
81
87
mean, g
1674
1708
NS
SD,
g
206
232
NS
All
N ,
no.
151
165
316
mean, g
1678
1687
NS
1683
SD,
g
202
217
NS
210
FXD
N ,
no.
50
mean, g
1670

SD,
g
211

38
2
14,500
PND
N ,
no.
100
65
165
mean, g
1562
1551
NS
1558
SD,
g
199
173
NS
189
FXD
N ,
no.
50

mean, g
1623

SD,
g
228
___
38
3
14,500
PND
N ,
no.
80
86
166
mean, g
1665
1564
*
1613
SD,
g
194
196
NS
201
FXD
N ,
no.
50

mean, g
1566

SD,
g
212

xt-test on sample means (P<.05).
2F-test ratio on sample variance (P<.05).
FDD= Feed dump location SD= Standard deviation
END= End location Sig= Significance (P<.05)
PND= All birds penned
FXD= Fixed quantity


6
traits can be utilized to alert the breeder manager to
ensuing increases in nutritional needs of the flock.
Hypothesis 4
If broiler breeders are severely feed restricted during
the rearing period and the resulting biological response is
an equivalent but delayed reproductive performance relative
to standard practices then, economic returns to the pullet
grower, hatching egg producer and broiler integrator from
restricted feeding will be increased above levels derived
from recommended practices.
Experimental Objectives
Regarding Hypothesis 1
The experimental objectives regarding hypothesis 1 were
to: 1. quantify the cyclic change in body weight over a 48
hour period;
2. illustrate the potential error in estimating weight
gain when weighings are not conducted at the same time each
weighing;
3. determine the effect of scale type, sample units,
sample size, sample location, time of sampling and
complexity of the procedures used in the on-farm weighing of
broilers, broiler breeder pullets and breeder hens, on
average body weight, body weight gain and uniformity;


49
during the hours of highest temperatures. An ERL feeding
schedule coupled with an evening weigh program is one
logical alternative; birds have settled down, voided most
feed, water and eggs, and temperatures are cooler. In this
scenario, variation in body weights as well as undue stress
could be minimized at no additional cost to the program.
Experiment 2
Scale type. Average body weight estimates measured on
the SPR scale were numerically higher but not significantly
different from measurements made on the ELC scale (Table 3-
2). The on-farm validation of these findings was upheld in
Experiment 3. An observation noted during these experiments
was that the automatic printing feature of the ELC scale
decreases the possibility of a transcription error and the
time (cost) necessary for weighing.
Sample unit. All trials conducted on-station
demonstrated that the average body weight determined by
individually weighing birds was not significantly different
than group weighing with crates of seven or eight birds
(Table 3-2). However, the estimates of flock uniformity as
measured by the standard deviation (SD) among observations
was significantly greater and more representative of the
true flock uniformity, when birds were weighed individually.


16
Payne, C. G., 1975. Day-length during rearing and the
subsequent egg production of meat-strain pullets. Br.
Poult. Sci. 16:559-563.
Pearson, R. A., and K. M. Herron, 1980. Feeding standards
during lay and reproductive performance of broiler
breeders. Br. Poult. Sci. 21:171-181.
Pearson, R. A., and K. M. Herron, 1981. Effects of energy
and protein allowances during lay on the reproductive
performance of broiler breeder hens. Br. Poult. Sci.
22:227-239.
Pearson, R. A., and K. M. Herron, 1982a. Effects of
maternal energy and protein intakes on the incidence of
malformations and malpositions of the embryo and time
of death during incubation. Br. Poult. Sci. 23:71-77.
Pearson, R. A., and K. M. Herron, 1982b. Relationship
between energy and protein intakes and laying
characteristics in individually-caged broiler breeder
hens. Br. Poult. Sci. 23:145-159.
Perry, G. C., D. R. Charles, P. J. Day, J. R. Hartland, and
P. G. Spencer, 1971. Egg-laying behavior in a broiler
parent flock. World/s Poult. Sci. J. 27(abstr.):162.
Peterson Farms, 1988. Broiler breeders management guide.
Decatur, AR.
Petitte, J. N., R. O. Hawes, and R. W. Gerry, 1981. Control
of flock uniformity of broiler breeder pullets through
segregation according to body weight. Poultry Sci.
60:2395-2400.
Petitte, J. N., R. 0. Hawes, and R. W. Gerry, 1982. The
influence of flock uniformity on the reproductive
performance of broiler breeder hens housed in cages and
floor pens. Poultry Sci. 61:2166-2171.
Petitte, J. N., R. O. Hawes, and R. W. Gerry, 1983. The
influence of cage versus floor pen management of
broiler breeder hens on subsequent performance of cage
reared broilers. Poultry Sci. 62:1241-1246.
Proudfoot, F. G., H. W. Huan, and K. B. McRae, 1980. The
effect of several different photoperiods on the
performance of meat-parent genotypes. Can. J. Anim.
Sci. 60:21-31.


The degree of sensitivity to energy intake is also
dependent on the season of the year. Chaney and Fuller
(1975) and Luther et al. {1976} reported that egg production
and egg size are reduced more severely by a decrease in
energy intake during the winter than during the summer,
since the energy requirement for maintenance of body
temperature is higher in the winter there are fewer calories
that remain for egg production. These authors suggested
that obesity per se does not reduce egg production since fat
birds can lay at a normal rate, but the obese birds suffer
from excessive mortality which results in depressed levels
of hen-housed production. In addition, McDaniel et al.
(1981a) and Pearson and Herron (1981) demonstrated that
over-consumption of energy by broiler breeder hens adversely
affected hen-day egg production, fertility, hatchability and
specific gravity.
Energy
A successful feeding program based on energy
restriction demands an easily applied and practical
guideline. Bornstein et al. (1979) suggested that the use
of average daily weight gain as an indicator of the degree
of energy restriction would be appropriate. Likewise,
Pearson and Herron (1980, 1981) recommended that body weight
control during egg production be considered as a criterion
for assessing the adequacy of energy intake. The
consequence of this recommendation was clearly illustrated


-24% treatment. At this age, specific gravity values are
increasing for the -24%, whereas, the values for STD have
already peaked and are decreasing. At the end of the
production cycle, egg weights converged and an improvement
in specific gravity was found which weakened the negative
correlation between these parameters. This could be
explained, in part, by the return of cooler ambient
temperatures.
Fertility and Hatchability
Data presented in Table 4-7 demonstrate that
quantitative differences in feed restriction, even severe
feed restriction, did not have a significant effect on
fertility or total hatchability at any age. Moultry (1983)
reported lower levels of fertility and hatchability from
those birds on severe restriction during rearing and lay.
Feed Usage
Cumulative intake of feed, crude protein (CP) and
metabolizable energy (ME) are presented in Table 4-8 on a
chronological and physiological basis. Proportional
differences in quantities of feed, CP and ME for all
treatments were a result of the feed allocation program
which was used to maintain parallel growth curves. When
measured to the common chronological age of 65 wk the -24%
treatment consumed 5.02 kg less feed, .71 kg less protein,
and 15.16 Meal less energy per hen housed for growth,
maintenance and production than did the STD. On a


119
When dwarf broiler breeders were fed according to
standard feeding recommendations, differences in rearing
costs among strains were due to the incidence of mortality
and age at which death occurred (Proudfoot et al., 1985).
The hypothesis to be tested in this analysis can be
stated as follows: If broiler breeders are severely feed
restricted during the rearing period compared to current
recommendations and the resulting biological response is an
equivalent but delayed reproductive performance relative to
standard practices (Chapter IV), then economic returns to
the pullet grower, hatching egg producer and broiler
integrator from severe feed restriction will be increased
above levels currently derived from recommended practices.
The specific objectives of this analysis were to:
1) examine the effect of feed restriction on pullet rearing
cost structure; 2) determine the cost of extending the
rearing period (delayed sexual maturity) due to various
levels of feed restriction; 3) test the sensitivity of
pullet rearing average total costs to changes in component
costs; 4) compare average total costs of hatching egg
production for various degrees of feed restriction; 5) test
the sensitivity of average total costs of hatching egg
production to changes in component costs; 6) determine the
changes in cost structure during the rearing period due to
changes in the density of pullets per unit area; and


38
Second, 25% resulted from two ova, which were developing a
day apart, being ovulated simultaneously. Third, the
remaining 10% resulted from successive development and
release of two ova, one remained in the body cavity for a
day and was then picked up by the oviduct along with the
newly released ovum. Zelenka et al. (1986) suggested that
the main cause of double-yolked eggs is that two ova reach
maturity and are released at the same time. They also
reported on the unusual situation where two ova can develop
and be released from a single ovarian follicle. They
suggested that this may have resulted from two separate and
distinct oocytes being encapsulated together by granulosa
layer cells during the intitial stages of follicular
development, or incomplete separation of oocytes following
meiotic cytokinesis.
Dobbs and Lowry (1976) utilized dietary dyes to
demonstrate that, in most cases, both yolks were ovulated
within 2 to 3 h of each other. Lowry et al. (1979) reported
that 80% of the pairs developed at the same time and that
ovulation sites were found to occur at random on the surface
of the ovary.
Hormonal mechanisms that control the development of the
ovarian follicular hierarchy were reported by Sharp et al.
(1976) who concluded that multiple ovulation in a super
ovulatory line of chickens was not due to a defect in the
luteinizing hormone releasing mechanism but to an abnormal


DOLLARS / PULLET SURVIVOR
145
PRICE SITUATIONS
FIGURE 6-4. Sensitivity of pullet average total cost to
changes in component costs at 20, 25, and 30 weeks of age for
the -24% feeding program.


50
Experiment 3 (on-farm^
Location Effect
^.'fo-'^^-dhtrun broilers. Body weight and body weight
uniformity estimates for the FDD and END house locations are
presented in Table 3-3. In general, broiler weights and
flock uniformity were not found to be different between
locations. There was a significant difference in average
body weight in Trial 3, which was attributed to the chance
occurrence of a slightly higher ratio of males sampled at
the FDD location at that particular sampling.
Pullets. Average body weight was not found to be
different between locations in either trial or at the ages
tested (Table 3-4). This observation would tend to be
consistent with findings of Van Krey and Weaver (1988) in
which it was shown that all semblance of social order
disappears during the period of frenetic feeding.
Significant differences in uniformity were found at the two
locations in trial one at 8 and 10 wk of age. The greater
variation at the FDD location was attributed to including
suspect outliers in the sample. Removal of these
observations on the basis of their being true outliers, as
shown in Table 3-7, resulted in levels of uniformity at both
locations that were no longer significantly different.
Breeders hens. A statistical difference in average
body weight of breeder hens due to house location was found
in Trial 1 at 36 and 38 wk of age without there being a


19
the electronic scale closer to the manual estimates for body
weight and uniformity.
A recent study on filial and sexual imprinting in
precocial birds (Lavie, 1988) showed that broiler chicks
raised on a commercial farm can be attached to and follow an
imprinting stimuli during the rearing period. Chicks were
subjected to a 3 wk imprinting process from day of age. The
stimulus was comprised of plastic boxes containing a music
cassette that was turned on for 10 minutes every 40 minutes
through 3 wk of age in the brood area of a house. After 3
wk the boxes were placed over the full length of the house
drawing imprinted birds to their new location. Relocation
for the imprinted birds was significantly better than
controls. This report confirmed results of an earlier study
by Gvaryahu et al. (198?) who demonstrated that meat strain
chicks can be attracted to an imprinting stimulus, and the
imprinting object could then be used to move birds from a
training area to a new location. More recently Gvaryahu et,
al. (1989) reported that filial imprinting results in
reduced stress behavior and improvements in growth
performance in male chicks. The implication here is the
potential use of imprinting behavior on the automatic
weighing systems. Blockhuis et al. (1988) began their study
at 4 wk of age with no attempt at familiarizing the birds
with the new scales


22
Studies undertaken to compare the growth and uniformity
of birds reared under skip-a-day and daily feeding programs
(Bennett and Leeson, 1989b) showed that body composition and
flock uniformity were unaffected by feeding program. Daily
feeding increased body weight gain indicating that feed is
more efficiently utilized under this feeding program. Those
researchers as well as Lilburn (1986) noted more aggressive
feeding behavior when birds were fed daily.
Comparison trials evaluating a skip-a-day with a skip-
two-days feeding program (Bartov et al.. 1988) found that
body weights of birds on the skip-two-days program were
significantly less, but maintained significantly better
levels of uniformity than birds fed on a skip-a-day program.
The decrease in body weight was also associated with a
significant delay in the onset of production, however, no
differences in production to 35 wk of age was detected.
Uniformity:
The importance of flock uniformity is underscored in
nearly every broiler breeder management guide and poultry
production book available to producers, uniformity is
usually measured as the percent of the birds that weigh
within + 10% of the average flock weight (North, 1984).
Acceptable uniformity is when 80% of the birds are in that
weight range. Relatively poor uniformity can result in a
production cycle that is characterized as having a slow
increase to peak production, never reaching a high peak


162
Cave, N. A., 1984b. Effects of a high-protein diet fed
prior to the onset of lay on performance of broiler
breeder pullets. Poultry Sci. 63:1823-1827.
Chaney, L. W., and H. L. Fuller, 1975. The relation of
obesity to egg production in broiler breeders. Poultry
Sci. 54:200-208.
Christmas, R. B., and R. H. Harms, 1982. Incidence of
double yolked eggs in the initial stages of lay as
affected by strain and season of the year. Poultry
Sci. 61:1290-1292.
Conrad, R. M., and D. C. Warren, 1940. The production of
double yolked eggs in the fowl. Poultry Sci. 19:9-17.
Cook, R. E., 1988. Poultry research programs in the future.
Poultry Sci. 67:890-896.
Costa, M. S., 1981. Fundamental principals of broiler
breeders nutrition and the design of feeding
programmes. World/s Poult. Sci. J. 37:177-192.
Craig, J. V., and A. M. Guhl, 1969. Territorial behavior
and social interactions of pullets kept in large
flocks. Poultry Sci. 48:1622-1628.
Dobbs, J. D., and D. C. Lowry, 1976. Yolk deposition in
double yolked eggs in a line of chickens selected for
simultaneous multiple ovulations. Poultry Sci.
55:2029.
Feighner, S. D., E.F. Godowsky, and B. M. Miller, 1986.
Portable microcomputer-based weighing systems:
Applications in poultry science. Poultry Sci. 65:868-
873.
Folch, J., M. Lees, and G. H. Sloan-Stanley, 1957. A simple
method for the isolation and purification of total
lipids from animal tissue. J. Biol. Chem. 226:497-
509.
Fuller, H. L., D. K. Potter, and W. Kirkland, 1969. Effect
of delayed maturity and carcass fat on reproductive
performance of broiler breeder pullets. Poultry Sci.
48:801-809.
Fuquay, J. I., and J. A. Renden, 1980. Reproductive
performance of broiler breeders maintained in cages or
on floors through 59 weeks of age. Poultry Sci.
59:2525-2531.


54
Sample size relative to flock size was determined by
sequentially adding 10 pullets or 20 breeders to their
respective samples, while evaluating the change in variance
as measured by the standard deviations, Table 3-8. A
stabilized level of sample variance would indicate that the
sample size achieved a level where additional observations
would not change the estimate of the population variance.
The sample variance peaked with a sample size slightly under
one percent of the population for the straight-run broilers
and pullets tested in these trials. Estimated sample
variance in a breeder flock peaked at only 0.5% of the
population. These levels of peaked variance would define an
absolute minimum sample size that could be used to estimate
flock body weight and uniformity.
It is known that the statistical accuracy of a sample
estimate generally increases with the sample size as a
percent of the flock size, number of sampling locations
selected per house, and the complexity of the sampling
procedures used. However, an increase in the sample size,
and/or number of locations will increase the cost of
weighing and disrupts the flock. Therefore, the choice of
an appropriate method of weighing broilers, broiler breeder
pullets, and breeder hens is primarily concerned with
maintaining the proper balance between the sample size and
number of locations that achieve a minimum cost without


13
mathematical value to compare the variation from flock to
flock. The use of sample variance in testing sample
adequacy when weighing broilers was also demonstrated by
Jaap (1955). Jaap recommended weighing ca. 25 birds from 3
locations in a house to estimate the average weight of a
flock of broilers.
gaBESS.g--.of... .Variation
Lilburn et.al. (1987) reported that breeder pullets fed
every day were significantly heavier at each age measured
than those fed every other day, even though mean cumulative
feed intake was not significantly different between
restriction treatments. They noted that part of this extra
body weight in the every~day treatment could be the result
of feed in the crop at the time of weighing. A.more recent
publication (Bennett and heeson, 1989b) comparingskip-a-day
and daily feeding programs, also noted that time of weighing
and feed retention in the digestive tract can strongly
influence the interpretation of growth trials with broiler
breeders.
Meal feeding in broilers was shown to increase
variability of body weights resulting from increased
variability in quantity of crop contents (May et_jyL., 1988,
and Vdrgara et al.. 1989). This finding was shown to be
complicated further by environmental temperatures lower
temperatures increased feed intake and variability in crop
content.


43
of Experiment 1 were to quantify the cyclic nature of body
weight gain in a 48 h period and to demonstrate the degree
of error in estimating gain when weighing programs are not
scheduled at a consistent time interval. The objectives of
Experiment 2 (on-station) and 3 (on-farm) were to determine
the effect of scale type, sample units (individual vs.
group), sample size, sample location, time of sampling, and
complexity of procedures used in the on-farm weighing of
broilers, broiler breeder pullets and breeder hens on
average body weight gain and uniformity.
Materials and Methods
Experiment 1
Trials 1 and 2. Eight pens containing 16 Arbor Acres
broiler breeder females, 25 wk old and not yet in
production, were divided into two feeding programs. The
first, an early feeding time (ERL) allocated 122 g of
feed/bird/d at 0430 h and the second, a late feeding time
(LTE) allocated an equivalent amount of feed at 1530 h.
Each feeding program consisted of two groups of two pens
each with a significant difference in average body weight
between groups. These weight class groupings (trials) could
then simulate different houses or farms and the effect of
initial body weight evaluated. Each pen was weighed, eight
birds per crate (two crates per pen), at 2 h intervals
starting at 0430 h and ending at 2030 h on the first day,


breeder caused by differences in the physical and managerial
environments in which they are reared and bred. Those
managers who approach breeder reproductive performance from
a life cycle perspective will find that maintaining the
proper balance between controlled growth and reproduction is
an easier task than those who do not.
Eesearchable Problems.
The primary objective of a broiler breeder management
program is to carefully monitor and control each phase of
growth and development during the life cycle. Breeder
managers are required to constantly make decisions
concerning feed formulation and allocation based on body
weight information generated from a pullet weighing program
or body weight and egg production information in the breeder
hen program. Inaccurate information will result in
inefficient and sometimes costly decisionscostly to the
integrator (increased chick cost), hatching egg producer
(lower payments) and society as a whole (higher meat cost)
as resources are not used efficiently.
The researchable problems identified in this
dissertation relate to this decision making process on the
part of the breeder manager. Specifically, the researchable
problems arise from the breeder managers need to 1)
establish an effective body weight monitoring and control
program, 2) maximize the number of placeable chicks from a


CHAPTER V
CHARACTERIZING THE ONSET OF SEXUAL MATURITY
IN FEED RESTRICTED BROILER BREEDER FEMALES
Introduction
The prime objective of a broiler breeder feeding
program is to maximize the number of chicks/hen at the
lowest cost possible. Realization of this objective
requires that a breeder manager achieve a target body weight
at a target age and a high degree of flock uniformity (Arbor
Acres, 1985). The importance of targeting sexual maturity
is a practical issue where economic considerations are
usually of greater concern than the need to understand the
physiological changes that occur at this time. Yet, if the
art of targeting sexual maturity in feed restricted broiler
breeder females is to be successful, then the science must
be understood and used to an advantage.
Numerous studies have been undertaken to determine the
mechanisms involved in the neuroendocrine initiation of
sexual maturity. Brody et al. (1980) postulated that both a
minimum body weight and chronological age are required for
sexual maturity while noting that a minimum fat content
might be necessary as well. The effects of feeding and
lighting programs on sexual maturity of different strains
92


122
became the fixed cost in the laying accounting period.
Table 6-2 lists the pullet rearing costs for each level of
feed restriction based on pullet rearing costs detailed in
Table 6-1.
variable costs
Feed costs
Pullet (PFD) and breeder hen (BFD) feed costs for a
particular age were determined by accumulating the product
of the base feed cost ($.135/kg) for pullets or {$.125/kg)
for breeder hens and the appropriate quantity of feed
consumed by birds on a particular feeding program (Tables 6-
1 and 6-2). Cumulative feed consumption was obtained from
experimental data and feed costs included a provision for
medication and delivery costs.
Serviceand supervision costs
Pullet (PSRV) and breeder hen (BSRVj service and
supervision costs were determined for a particular age by
projecting a linear increase in cumulative costs at the
estimated base rate of $.013 /pullet/wk for the pullet
rearing enterprise or $.0075 /dozen hatching eggs (DZHE) for
the breeder hen laying enterprise. At these rates, the
total cost per pullet reared from l wk through 25 wk of age
was $.325 /pullet survivor and the total cost per DZHE
through 40 wk of production was $.30 /DZHE.


32
well beyond a normal age, birds did not fully compensate in
growth. Instead body weights remained about 25% lighter
than mature body weights of the control group, When the
severely restricted birds were changed to an ad libitum
feeding program, sexual maturity ensued in a uniform manner.
This study concluded that a minimum body weight and
chronological age were required for the onset of sexual
maturity.
In 1984 five papers on the subject of sexual maturity
appeared, four utilizing broiler breeders and one using
Japanese Quail. Seller et al. (1984b) demonstrated that
body fat content or fat percentage alone is not sufficient
to initiate sexual maturity. More importantly they
concluded that there is a minimum lean body mass requirement
for the onset of sexual maturity in poultry. This finding
was also reported by Zelenka et al. (1984) and Oruwari and
Brody, (1988) with Japanese quail,
Bornstein et al. (1984) confirmed findings of a minimum
requirement for fat and lean tissue stores in conjunction
with chronological age and demonstrated that these
thresholds are strain specific. These researchers, as well
as Pearson and Herron (1982a), reported a significant
negative correlation between age and body weight at first
egg.
Comparisons made by Brody et al. (1984) between normal
and dwarf strains of broiler breeders illustrated the extent


33
to which differences in body weight and age at sexual
maturity can be affected by genetic variation. Age at first
egg ranged from 153 to 173 d in normal breeders and 167 to
173 d in dwarf breeders. The greatest difference between
pullets at sexual maturity and their nonlaying controls were
in the size of the abdominal fat pad and the reproductive
organs. This result suggests that increases in fat prior to
sexual maturity, instead of being general to the carcass,
are restricted to a few organs related to the partitioning
of energy for reproductive performance.
Breeder Hen Laving Period
Because mature broiler breeders are capable of
consuming feed far in excess of their energy requirement for
maintenance and egg production it is economically
advantageous to formulate broiler breeder hen diets on a
daily nutrient intake basis (Wilson and Harms, 1984).
Pearson and Herron (1981) noted that broiler breeder hens
are sensitive to energy intake during the breeding period.
Extra dietary energy enabled birds to gain more weight (fat)
and this had a depressing effect on egg production,
fertility and hatchability (Pearson and Herron, 1982a;
Spratt and Leeson, 1987a). Furthermore, as the rate of lay
decreases, more energy is available for fat deposition so
the initial negative effects on production are likely to be
maintained or increased through lay.


Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy
BIO-ECONOMIC ANALYSIS OF SELECTED
BROILER BREEDER MANAGEMENT PRACTICES
BY
THOMAS RICHARD FATTORI
December, 1989
Chairman: Henry R. Wilson
Cochairman: Peter E. Hildebrand
Major Department: Animal Science (Poultry Science)
Studies were conducted to evaluate bird weighing
procedures and the effect of selected broiler breeder
management practices on pullet and breeder hen growth and
reproductive performance.
Evaluations were made of the effects of sample and
batch size, in-house locations, type of scale, time of
weighing and procedure complexity used in the on-farm
weighing of broiler breeder stock on body weight gain and
uniformity. Time of weighing was shown to be an important
source of error when estimating live weight gain. No
significant differences in average body weight due to scale
type or batch size could be detected. A significant
location effect was found with breeder hens, but not with
broilers or breeder pullets. It was determined that
suspected outliers should not be rejected from the sample.
xii


21
Behavior
Although feed restriction programs are currently
considered essential to ensure acceptable levels of
livability, fertility and hatchability, feed restriction
itself can cause marked behavioral and physiological changes
in growing birds. These effects can have a negative impact
on flock performance. Mench and Shea (1988) found that male
broiler chicks placed on a skip-a-day feeding program were
more aggressive than males fed ad libitum. This display of
aggression manifested more on the off-feed days than on the
feed days. Competition for food is generally considered a
strong stimulus for aggressive behavior. Aggressive
behavior (pecking activity) was shown to be age related with
peak aggression displayed between 9 and 10 wk of age. The
intensity of aggressive behavior shifted from higher levels
on off-feed days to higher levels on feed days by 24 wk of
age.
Van Krey and Weaver (1988) showed that broiler breeder
pullets provided only 45% of the recommended feeder space
responded in terms of growth and uniformity as well as, or
better than, those given 90% of the recommended feeder
space. They noted that all semblance of social order
disappears during the period of frenetic feeding immediately
after food is made available. As a result, all birds are
able to consume at least some feed despite very limited
feeder space.


170
Watson, N. A., 1975. Reproductve activity of broiler hens
subjected to restricted feeding during rearing. Br.
Poult. Sci. 16:259-262.
Whitehead, C. C., K. M. Herron, and D. Waddington, 1987.
Reproductive performance of dwarf broiler breeders
given different allowances of food during the rearing
and breeding periods and two lighting patterns. Br.
Poult. Sci. 28:415-427.
Williams, J. B., and P. J. Sharp, 1978. Ovarian morphology
and rates of ovarian follicular development in laying
broiler breeders and commercial egg-producing hens.
Br. Poult. Sci. 19:387-395.
Wilson, H. R., and R. H. Harms, 1984. Evaluation of
nutrient specifications for broiler breeders. Poultry
Sci. 63:1400-1406.
Wilson, H. R., and R. H. Harms, 1986. Performance of
broiler breeders as affected by body weight during the
breeding season. Poultry Sci. 65:1052-1057.
Wilson, J. L, and N. Dale, 1989. Effect of 20 week body
weight on subsequent performance of broiler breeder
hens. Poultry Sci. 68(Sup. 1):159.
Yu, J. Y. L., and R. R. Marquardt, 1974. Hyperplasia and
hypertrophy of the chicken (Gallus domesticus) oviduct
during a reproductive cycle. Poultry Sci. 53Roge
lios.
Zelenka, D. J., J. A. Cherry, I. Nir, and P. B. Siegel,
1984. Body weight and composition of Japanese quail
(Coturnix coturnix japnica) at sexual maturity.
Growth 48:16-28.
Zelenka, D. J., D. E. Jones, E. A. Dunnington, and P. B.
Siegel, 1987. Selection for body weight at eight weeks
of age. 18. Comparisons between mature and immature
pullets at the same live weight and age. Poultry Sci.
66:41-46.
Zelenka, D. J., P. B. Siegel, and H. P. Van Krey, 1986.
Ovum formation and multiple ovulation in lines of White
Plymouth Rocks and their crosses. Br. Poult. Sci.
27:409-414.


148
PRICE SITUATIONS
FIGURE 6-8. Sensitivity of breeder hen average total cost to
changes in pullet depreciation costs (PUL$) or costs due to
breeder hen mortality (BMRT) at 40 weeks of production for the
STD and -24% feeding programs.


138
TABLE 6-4. Effect of feeding program on pullet rearing
average cost budget through 5% production, calculated at
base prices
Feeding Program
+8%
STD
-8%
-16%
-24%
Performance factors
Age, wk
24
25
26
27
28
Livability
Pullet, %
.952
.950
.948
.946
.944
Cockerel, %
.880
.875
.870
.865
.860
Feed, Kg/Surv.
12.96
12.98
12.83
12.61
12.31
Averacre Fixed
Costs /
Pullet survivor AFC/P1
Chick, $
2.152
2.158
2.163
2.169
2.173
Averacre Variable Costs
/ Pullet
survivor (AVC/P)
Feed, $
1.750
1.752
1.732
1.702
1.662
Grower pay, $
1.213
1.266
1.320
1.373
1.427
PVAC1, $
.303
.316
.329
.343
.356
Service &
supervision, $
.328
.342
.357
.371
.386
Averacre Total
Cost / Pullet survivor (ATC/P)
ATC/P, $
5.745
5.834
5.901
5.958
6.005
1PVAC= Pullet vaccination, beak trimming, blood testing and
miscillaneous costs.


103
TABLE 5-2. Effect of feed treatment (mean + SEM) on various
attributes associated with sexual maturityr
Age Feed BWT FTPD LIPID
(wk) treat. (g) (g)(mg/mL)
20
+8%
2532

88a
70.8
+
4.4*
6.37
+
.38
STD
2156
4*
27b
50.1
+
4.7b
6.14

.34'
-8%
1945
+
32bc
29.8
4~
6.9C
5.89

.25
-16%
1752
4;
43c
12.7
+
4.6d
5.63

.13
-24%
1529

153d
7.7

6.4d
5.30
+
. 32
22
+8%
2651
49*
70.5
+
12.0
5,31

.11
STD
2334
t
39b
64.1
+
6.5*
5.03
+
.12
-8%
2182

23c
43.9
+
7.3*
4.99
j.
.16'
-16%
1941
+
48d
21.8
+
5.0b
4.51
+
.101
-24%
1710

39*
15.5
+
7.1b
4.54
t
. 171
24
+8%
2848
53*
127.0
+
18.9*
6.85
4.
1.23
STD
2835
+.
114
111.0
11.3*
4.75

.05'
-8%
2387
4;,
26b
57.2
+
3.9b
4.60

.08'
-16%
2250
+.
50b
59.3
+
11.3b
4.60
+
.14'
-24%
1891
+
16c
15.7
+
8.6C
4.45
.13'
26
+8%
3123
55
143.0
+
21.8*
12.10
+
2.78
STD
2950
+
160*
118.0
+
24.4*
10.40

1.03
-8%
2675
*4
64b
80.3
+
13.8be
5.05
+
l.ll'
-16%
2342
+
42c
31.6
+
5.8
4.65
+
.59'
-24%
2097
+
50d
29.7
+
15.3C
4.00

.32'
28
+8%
3018
113
104.0
+
o
o
M
17.60

2.72
STD
2886
+
131*
113.0
+
5.8
18.50
2.43
-8%
2713
79*
113.0
+
18.7*
14.50
+
4.18
-16%
2534
+
51b
75.2
+
18.2bc
9.15
+
2.071
-24%
2152
+
96
32.3
+
11.0
8.35

2.05
1BWT=body weight, FTPD=fat pad, LIPID=total plasma lipid are
only for those birds sampled and are not a treatment mean
for all birds.
'Means within a column and having no common superscript are
significantly different (P<05).


TABLE 3-1. Effect of feeding time (ERL vs. LTE) and time of day on non-laying broiler
breeder female mean body weight and weight change (Exp. 1)
ERLa
LTEa
Trial 1
Trial 2
Pooled
Trial 1
Trial 2
POOLED
Day
Time
(h)
BWT
(g)
Change
(g)
BWT
(g)
Change
(g)
BWT
(g)
Change
(g)
BWT
(g)
Change
(g)
BWT
(g)
Change
(g)
BWT
(g)
Change
(g)
1
04:00
04:30
2582
FEED
NA
2747
FEED
NA
2664
FEED
NA
2785
NA
2818
NA
2801
NA
06:30
2723
140
2864
118
2794
129
2774
NA
2806
NA
2790
NA
08:30
2755
173
2884
138
2820
155
2754
NA
2792
NA
2773
NA
10:30
2737
155
2883
136
2810
145
2724
NA
2774
NA
2749
NA
12:30
2725
143
2872
125
2798
134
2708
NA
2754
NA
2731
NA
14:30
15:30
2701
119
2842
95
2772
107
2676
FEED
NA
2727c
FEED
NA
2701
FEED
NA
16:30
2670
88
2816
70
274
79
2839
182
2889
176
2864
179
18:30
2670
88
2806
60
2738
74
2870
213
2910
197
2890
205
20:30
2647
65
2795
48
2721
57
2859
202
2896
183
2877
192
2
04:00
04:30
2601
FEED
19
2755
FEED
9
2678
FEED
14
2794
118
2822
95
2808
106
06:30
2747
165
2896
150
2821
157
2785
110
2815
88
2800
99
08:30
2769
188
2916
170
2842
179
2767
91
2813
86
2790
89
10:30
2772
191
2899
153
2835
172
2745
70
2802
75
2774
72
12:30
2750
168
2881
135
2816
152
2720
44
2779
52
2750
48
14:30
15:30
2727
145
2859
113
2793
129
2694
FEED
19
2757
FEED
30
2725
FEED
24
16:30
2700
118
2835
89
2767
104
2779
104
2832
105
2806
104
18:30
2679
97
2818
72
2748
84
2874
199
2910
183
2892
191
20:30
2663
81
2806
60
2735
71
2879
203
2900
173
2889
188
aERL= Early feed time (0430h); LTE= Late feed time (1530 h); NA=Not applicable.
bTrial 1 and 2, average of two pens.
Initial body weight prior to feeding.
ui


166
Meltzer, A., and D. Landsberg, 1988. The modern approach to
weighing poultry. Int. Hatchery Practice 2(6):27-29.
Mench, J. A., and M. M. Shea, 1988. Effects of feed
restriction and tryptophan on the behavior of broiler
breeders. In: Proc. Maryland Nutr. Conf., Poultry Sci
Dept., Univ. of Maryland, College Park, MD.
Montgomery, D. C., 1984. Design and Analysis of
Experiments. John Wiley and Sons, Inc., New York, NY.
Morris, T. R., 1967. Light requirements of the fowl. pp.
15-29 In: Environmental Control in Poultry Production.
T. C. Carter, ed. Oliver and Boyd, Edinburgh,
Scotland.
Moultry, F., 1983. Feeding and lighting trials with broiler
breeders a progress report. In: Proc. Arkansas Nutr.
Conf., Dept, of Animal Sciences, Univ. of Arkansas,
Fayetteville, AR.
Murphy, L. B., and A. P. Preston, 1988. Food availability
and the feeding and drinking behavior of broiler
chickens grown commercially. Br. Poult. Sci. 29:273-
283.
National Research Council, 1984. Nutrient Requirements of
Poultry. 8th ed. National Academy Press, Washington,
DC.
Newberry, R. C., J. R. Hunt, and E. E. Gardiner, 1985.
Behaviour of roaster chickens towards an automatic
weighing perch. Br. Poult. Sci. 26:229-237.
North, M. 0., 1984. Commercial Chicken Production Manual.
Third Edition. Avi Publ. Co., Inc., Westport, CT.
Ogunji, P. A., R. N. Brewer, D. A. Roland, Sr., and D.
Caldwell, 1983. Effect of sodium chloride, protein,
and strain difference upon water consumption and fecal
moisture of broiler breeder males. Poultry Sci.
62:2497-2500.
Oruwari, B. M., and T. Brody, 1988. Roles of age, body
weight and composition in the initiation of sexual
maturation of Japanese quail (Coturnix coturnix
japnica). Br. Poult. Sci. 29:481-488.
Patterson, P. H., M. L. Sunde, and J. L. Pimentel, 1989.
Water consumption and fecal moisture of laying hens fed
wheat middlings and corn-soybean-alfalfa meal diets.
Poultry Sci. 68:830-833.


59
TABLE 3-4. Effect of sample location (FDD vs. END) at
various ages and by sample type (PND vs. FXD) on mean pullet
body weight and uniformity (SD) (Exp. 3)
Trial 1
Trial 2
Age
Location
Location
(wk)
Time
Type
FDD
END
Sig.
FDD
END
Sig.
8
AM
PND
N no.
111
107
113
100
mean, g
855
847
NS
854
873
NS
SD, g
133
97
*
129
131
NS
FXD
N no.
60
60
60
60
mean, g
890
862
NS
866
884
NS
SD, g
142
97
*
131
133
NS
10
AM
PND
N no.
92
72
mean, g
991
1033
NS
1022
1033
NS
SD, g
146
140
NS
156
159
NS
FXD
N no.
60
60
60
60
mean, g 1031
1050
NS
1032
1027
NS
SD, g
138
134
NS
167
163
NS
10
PM
PND
N no.
88
96
___
mean, g
948
974
NS


SD, g
168
145
*

'
FXD
N no.
60
60


mean, g
974
984
NS


SD, g
162
143
NS

1 t-test on sample means (P<.05)
2 F-test ratio on sample variance (P<.05).
FDD= Feed dump location SD= Standard deviation
END= End location Sig= Significance (P<.05)
PND= All birds penned
FXD= Fixed quantity


TABLE 3-8. Effect of sample size on mean and variance of
body weight for broilers, pullets and breeder hens.
63
N
Mean
SD
N
Mean
SD
Breeder
hens
10
3560
233
10
3451
194
20
3465
301
20
3363
244
30
3433
382
30
3391
249
40
3394
360
40
3386
291
50
3411
343
50
3373
275
60
3414
333
60
3385
261
70
3387
326
70
3390
268
80
3384
316
80
3378
257
90
3387
305
90
3368
256
100
3387
297
100
3339
265
110
3357
318
110
3344
261
120
3353
309
120
3347
261
130
3364
312
130
3344
270
140
3364
320
140
3338
259
Broilers
Pullets
20
1707
161
20
870
123
40
1718
187
40
889
126
60
1702
198
60
885
113
80
1693
195
80
866
112
100
1687
201
100
862
111
120
1690
198
120
855
132
140
1693
201
140
859
128
160
1685
199
160
857
124
180
1680
200
180
860
119
200
1683
202
200
861
116
220
1683
212
220
853
117
240
1689
212
260
1690
211
280
1692
206
300
1676
206


137
TABLE 6-3. Average total cost of a pullet survivor reared
to common age on five feeding programs
Feeding Program
+8%
STD
-8%
-16%
-24%
Average Total Cost/
pullet survivor, $
20 wk
4.881
4.796
4.711
4.627
4.544
25 wk
5.967
5.834
5.700
5.567
5.436
30 wk
7.125
6.948
6.780
6.597
6.423


169
Soller, M., T. Brody, Y. Eitan, T. Angursky, and C. Wexler,
1984a. Minimum weight for onset of maturity in female
chickens: Heritability and phenotypic and genetic
correlations with early growth rate. Poultry Sci.
63:2103-2113.
Soller, M., Y. Eitan, and T. Brody, 1984b. Effect of diet
and early feed restriction on the minimum weight
requirement for onset of sexual maturity in White Rock
broiler breeders. Poultry Sci. 63:1255-1261.
Spratt, R. S., and S. Leeson, 1987. Broiler breeder
performance in response to diet protein and energy.
Poultry Sci. 66:683-693.
Strain, J. H., and A. W. Nordskog, 1962. Genetic aspects of
the profit equation in a broiler enterprise. Poultry
Sci. 41:1892-1902.
Stutz, M. W., D. E. Mayer, and J. P. Glatzhofer, 1984. An
automated weighing and analysis system for growth and
feed efficiency studies. Poultry Sci. 63:49-54.
Summers, J. D., W. F. Pepper, S. J. Slinger, and J. D.
McConachie, 1967. Feeding meat type pullets and
breeders. Poultry Sci. 46:1158-1164.
Turner, M. J. B., P. Gurney, and C. G. Belyavin, 1983.
Automatic weighing of layer-replacement pullets housed
on litter or in cages. Br. Poult. Sci. 24:33-45.
Van Krey, H. P., and W. D. Weaver, Jr., 1988. Effects of
feeder space on body weight uniformity of broiler
breeder pullets during an alternate day feeding
program. Poultry Sci. 67:996-1000.
Vergara, P., M. Jimenez, C. Ferrando, E. Fernandez, and E.
Gonalons, 1989. Age influence on digestive transit
time of particulate and soluble markers in broiler
chickens. Poultry Sci. 68:185-189.
Waldroup, P. W., and K. R. Hazen, 1976. A comparison of the
daily energy needs of the normal and dwarf broiler
breeder hen. Poultry Sci. 55:1383-1393.
Waldroup, P. W., K. R. Hazen, W. D. Bussell, and Z. B.
Johnson, 1976. Studies on the daily protein and amino
acid needs of broiler breeder hens. Poultry Sci.
55:2342-2347.


3
conversion are not as great as such progeny traits as yield
(with its associated characteristics, including grade and
conformation), feed conversion and growth rate in todays
market environment (Rishell, NA). A percentage change in
processing yield will have a greater effect on profits than
will an equal change in any of the other genetic traits
considered in a breeding program.
Problematic Situation
Different breeding policies among the various primary
breeders result in strains of birds that are suited for
different market conditions. This genetic variability can
be used to an advantage by broiler producers so that a
flexible production response to consumer demand can be
achieved. In fact it is not uncommon for a production
complex to utilize several commercial breeds at the same
time. The problematic situation being that each strain of
bird is best managed by a specific set of procedures.
A successful broiler breeder management program is one
that optimizes the use of feed, labor, capital and other
resources in the production of placeable chicks per hen
housed. The complexity of this challenge is made evident by
the depth and diversity of possible factors that can impact
either negatively or positively on the production process.
Management must account for and control variation in
the growth and development of a particular strain of broiler


142
TABLE 6-8. Live body weight (kg) by feeding program at
various transfer (laying house) ages and the relative
differences (%) among programs
Feeding Program
+8%
STD
-8%
-16%
-24%
Live weiaht.
(kg)
22 wk
2.48
2.33
2.11
1.89
1.75
24 wk
2.84
2.58
2.37
2.13
1.97
26 wk
3.09
2.85
2.61
2.33
2.18
Relative differences in
live weight from
std. m
22 wk
+6.0
-9.4
-18.9
-24.9
24 wk
+9.2
*
-8.1
-17.4
-23.6
26 Wk
+7.8
-8.4
-18.2
-23.5
Adiusted bird
densitv1
Potential
-7%
-
+7%
+14%
+21%
Adjusted base
bird density,
mVpullet
Ftz/pullet
.174
1.872
.163
1.750
.151
1.628
.140
1.505
.128
1.382
ATC/P
at 5% prod.
5.745
5.834
5.901
5.958
6.005
Adjusted
ATC/P
5.830
5.834
5.809
5.765
5.705
Potential adjustment in bird density relative to STD with a
margin of safety to maintain an equivalent bio-mass at
various transfer ages.


14
Feed restriction influences total water intake as well
as the cyclic patterns of water consumption (Bennett and
Leeson, 1989a). These researchers reported that boredom and
hunger were not the main stimuli of the cyclic pattern of
water consumption associated with feeding programs; they
concluded that the meal on the on-feed day had a much
stronger influence on water consumption than hunger or
boredom on the off-feed day. Quantities of water consumed
can also be affected by diet ingredients. Patterson et al.
(1989) demonstrated that water intake can be increased by as
much as 1.5 times when feeding high fiber ingredients (wheat
middlings) as compared to a lower fiber corn-soy diet. They
also reported that the form of feed can influence water
intake and showed that pelleted feed will increase water
intake over mash. Birds fed high fiber diets tend to eat
more feed to achieve an equivalent intake of energy than
birds on a low fiber diet. This suggests that it is both the
quantity of feed as well as the fiber content that leads to
increased water intake.
Water consumption is also influenced by the strain of
bird used in production (Ogunji et al., 1983). These
researchers reported significant differences in water intake
for two breeder male strains known to exhibit differences in
loose droppings. They also demonstrated that dietary
protein had no significant influence on water consumption.
However, fecal moisture increased as dietary protein


4-3 Effect of feed treatment on growth, development
and mortality of breeder hens 82
4-4 Effect of feed treatment on breeder hen mean
( SEM) production performance 83
4-5 Effect of feed treatment on hen-day production
for chronological and physiological ages 84
4-6 Effect of feed treatment on mean (+ SEM)
specific gravity (SG) and egg weight (EW), and
the correlation between these parameters at
various ages 85
\
4-7 Effect of feed treatment on mean ( SEM)
hatchability of all eggs set (Hatch) and
fertility (Fert) at various ages 86
4-8 Cumulative feed, crude protein and metabolizable
energy intake per bird at various chronological
and physiological ages and by feed treatment 87
5-1 Correlation coefficient (r) and the significance
probability that the correlation is zero (P>/r/)
for various physical attributes associated with
sexual maturity 101
5-2 Effect of feed treatment (mean + SEM) on various
physical attributes associated with sexual
maturity 103
5-3 Effect of feed treatment on bursa weight (mean +
SEM) and relative proportion of bursa and fat pad
to body weight 105
5-4 Effect of feed treatment (mean + SEM) on various
physical attributes associated with sexual
maturity 106
6-1 Base costs, production coefficients and +20%
adjustments used in sensitivity analysis of a
pullet rearing enterprise 135
6-2 Base costs, production coefficients and 20%
adjustments used in sensitivity analysis of a
breeder hen laying enterprise 13 6
6-3 Average total cost of a pullet survivor reared
to a common age by feeding program 137
vii


7
and 4. determine the effect of subjectively removing
suspected outliers from a sample group on average body
weight estimates and uniformity.
Regarding Hypothesis 2
The experimental objectives regarding hypothesis 2 were
to: 1. evaluate the broiler pullet growth response to
various degrees of severe feed restriction;
2. evaluate the breeder hen growth and production
response to various degrees of severe feed restriction;
3. evaluate changes in reproductive physiology related
to severe feed restriction;
4. evaluate the effect of severe feed restriction on
hatching egg characteristics;
and 5. evaluate breeder hen technical efficiencies related
to feed usage and production performance.
Regarding Hypothesis 3
The experimental objectives regarding hypothesis 3 were
to: 1. quantify the effect of severe feed restriction on
various physical attributes associated with sexual maturity
through the pullet-layer transition period;
2. assess the degree of linear correlation among all
quantified physical attributes at various ages;


105
TABLE 5-3. Effect of feed treatment on bursa weight (mean +
SEM) and relative proportion of bursa and fat pad to body
weight
Age Feed BURSA BURSA: BWT* FTPD:BWT
(wk) treat. (g) (g/g) (g/g)
20
+8%
2.63
.48a
.10
.02*
2.80
+ .14*
STD
2.53
.13
.12
.01*
2.15
.31ab
-8%
1.72
. 15ab
.09
+ .01b
1.52
-32b0
-16%
1.47
+ .19b
.08
.01b
.73
+ .25cd
-24%
2.02
.21*
.14
.01*
.45
.32d
22
+8%
2,61
*54*
.10
.Q2a
2.65
*43*
STD
2.48
.63*
.11
+. 03a
2.72
.25*
-8%
2.00
. 27a
.09
*01a
1.97
.31ab
-16%
1,78
+ .32*
.09
02*
1.10
.23bc
-24%
1.75
.22a
.11
01*
.90
. 39*
24
+8%
2.82
.39^
.10
*02*
4.42
+ .61*
STD
2.54
*15
,09
.01*
3.90
. 32*b
-8%
3,37
. 68a
.14
03*
2.40
. 17b
-16%
2.47
*30*
.11
+ .01*
2.62
+ 44ab
-24%
2.00
.09b
.11
o*
.85
.46c
26
+8%
2.88
, 30*
.09
.01*
4.58
. 62*
STD
1.77
.08bc
,06
+ ohc
3.97
62*
-8%
1.40
.12c
.05
+ 0
3.00
, 48ab
-16%
2.58
+ .66*
.11
+ .03*
1.35
+ .24bc
-24%
1.52
.17bc
.07
.01Ac
1.37
. 70c
28
+8%
1,05
*33*
.04
+ .01b
3.43
+ .59*
STD
1.60
.66a
.05
.02b
3.95
30*
-8%
2.29
. 74a
,08
+ .03ab
4.10
+ .58*
-16%
1.25
.51*
.05
+ .02b
3.00
+ .70*
-24%
2.48
. 73a
.12
04*
1.47
.43b
1BOT=Body weight: FTPD=Fat pad.
a'dMeans within a column and having no common superscript are
significantly different (P<.05).


40
the number of settable eggs during this period (Fuller et
al. 1969; Chaney and Fuller, 1975? Zelenka et al.. 1986;
Hocking et al., 1987, 1989? and Katanbaf et al.. 1989b).
Hocking et al. (1989) reported that feed restriction which
resulted in the reduction of the number of yellow follicles
at sexual maturity was associated with lighter, leaner birds
with lower maintenance requirements, but delayed sexual
maturity. Heavier birds were associated with higher numbers
of follicles, whereas, fatter birds were associated with
fewer numbers of follicles. This suggests that a positive
relationship exists between ovulation rate and lean tissue
mass. These authors recommend that feed restriction should
be continued to point of lay.


73
uniformity for the most restricted birds was suspected but
not substantiated. Blair et al. (1976) and Lee et al.
(1971) reported that an apparent disadvantage to feed
restriction was a possible negative effect on flock
uniformity. The effect of feed treatment on mean body
weight was still significant through 62 wk of age and the
-24% treatment maintained a mature body weight 255 g lighter
than STD. This was similar to findings by Brody et al.
(1980) who showed that after severe feed restriction, body
weights remained about 25% lighter than the mature body
weights of a control group. Uniformity at 62 wk improved
from 20 wk levels indicating that body weight distributions
seem to stabilize as the flock achieves a mature body
weight. Shank length was significantly and permanently
decreased by the -16% and -24% treatments (Table 4-3),
which indicates a stunting of the birds mature frame size.
Flock Maturation
Feed treatment had a significant effect in delaying the
onset of flock maturity (50% production). Mean age and body
weight at 50% production for each treatment are presented in
Table 4-3. To test the hypothesis that a reduction in body
weight will delay flock sexual maturity, the dependent
variable body weight (Y, kg) was regressed on the
independent variable age (X, days) at 50% production (Figure
4-3). The resulting negative linear regression equation,
Y = 5.737 .0137 (X),
Std. Err. (.426) (.002)
Prob. .0001 .0001,


6-4 Effect of feeding program on pullet rearing
average cost budget through 5% production,
calculated at base prices 138
6-5 Effect of feeding program on breeder hen average
cost budget through 40 weeks of production,
calculatd at base prices and expressed as
dollars per survivor 139
6-6 Effect of feeding program on breeder hen average
cost budget through 40 weeks of production,
calculated at base prices and expressed as
dollars per dozen hatching eggs 140
6-7 Average total cost of a dozen hatching eggs
produced to a common age by feeding program,
calculated at base prices and before salvage
adjustments 141
6-8 Live body weight (kg) by feeding program at
various transfer (laying house) ages and the
relative difference (%) among programs 142
viii


124
Payments to the hatching egg producer (BPAY) were
calculated based on the estimated contractual base rate of
$.30 /DZHE which included payment to the producer for egg
salvage (commercial eggs @ $.10 /DZ) and any potential
bonus.
Vaccination. Beak Trimming and Blood Testing Costs
Pullet vaccination, beak trimming, blood testing and
miscellaneous costs (PVAC) were determined by increasing
PVAC costs linearly from 1 wk of age at the rate of $.012
/pullet. At this rate the cumulative PVAC costs amounted to
$.30 /pullet at 25 wk of age.
Salvage Prices
Commercial egg salvage values (ESLV) received by the
integrator were determined for each feeding program by
multiplying cumulative commercial egg quantities at a given
age by the estimated salvage base price of $.10 /dozen.
Bird salvage values (BSLV) were determined for each
feeding program by multiplying the estimated salvage base
price of $.286 /kg of live bird by the average live body
weight of birds at a particular age.
Average Total Cost
Pullet rearing period. The total cost of rearing a
pullet was equal to the summation of fixed costs (CHK) and
variable costs (PFD, PPAY, PSRV and PVAC) for a particular
age. since the technical output of the pullet rearing
process is numbers of live pullets, livability data derived


104
TABLE 5-2. Continued
Age Feed OVARY OVIDUCT
(wk)
treat,
(g)
(g)
20
+8%
53
. 03a
.53
+
.05
STD
.50
i
.04
.48

.05a11
-8%
.38

.03
* 30
t
.04
-16%
.40

0
.33
jh
. 03fco
-24%
.40

.11
.30
i
.07
22
+8%
1.02
+
.19
1.62
4*
.27
STD
. 66
Hh
* Q3b0
1.44
i
. 80th
-8%
.86

. 05ab
1.19
4*
,30th
-16%
.58
4.
.04
.57
,03b
-24%
.54

. 02c
.43
. Q4b
24
+8%
11.30

9.99
16.10
+
9.69
STD
.75
.04
3.21
. 78ab
-8%
.82
.02
1.20

. 27b
-16%
1.03
.24
7.37
+
3.97a53
-24%
.88

.03
.59

. 09b
26
+8%
3.52
nr
1.59b
15.80
4-
4.23ab
STD
6.83
+
4,16th
27.40

8.27
-8%
32.30
4,
18.50
35.40
11.80*
-16%
1.46
4.
. 32b
7.37
i
3.72bc
-24%
.81

. 29b
1.41

.80
28
+8%
34.80
+
14.40
52.10
7.66
STD
24.40
Hk
13. 40abc
37.40

12.50
-8%
3.85
+
1.47bc
20.30

6.37
-16%
37.10
Hh
20.70^
33.80
i
12.20
-24%
1.52
+
.46
5.16

3.85b
'Means within a column and age having no common superscript
are significantly different (P<.05).


74
indicates that for every 13.7 g decrease in body weight,
within the range of body weights and ages at flock maturity
found in this experiment, there was a corresponding delay in
flock maturity by 1 day. The resulting negative correlation
(r = -.84) was significant and is in agreement with findings
by Pearson and Herron (1982b) who also reported a
significant negative correlation (r = -.88) between these
factors.
Mortality
Mortality was not affected by feed treatment over the
life of the flock or when analyzed by pullet or breeder hen
phase of growth (Table 4-3). The levels of mortality for
all treatments were low compared to levels commonly found in
industry. Difficulty in detecting differences among
treatments was due to high levels of between-replicate
variation. There was a trend, although not significant, for
the -24% birds to have higher mortality in the pullet
rearing period and lower mortality in the breeder hen laying
period. This trend would be in agreement with observations
made by Pym and Dillon (1969, 1974) who noted that the net
effect of high rearing and low layer mortality would be no
difference in overall mortality, bee et al., (1971) cited
numerous reports of lower mortality during the laying period
in birds restricted during rearing. From an economic
perspective this would be an advantage due to the higher
value associated with the breeder hen.


11
the literature. Environmental effects such as photoperiod,
temperature, humidity, and air and litter quality have a
strong influence on maintenance, growth and production.
Pullet management can interact with breeder management,
especially when birds are moved into new housing for
production. Differences in breeder strain, housing,
equipment, feed ingredients, and feed and water quality can
all be a source of variation in commercial performance as
well as experimental discrepancy or error.
This review will examine the following areas of
interest: weighing programs and pullet rearing, pullet-layer
transition, and breeder hen laying periods.
Weighing Programs
Weighing Methodology
A review of the current broiler breeder management
guides revealed a broad range of recommended sample weighing
techniques. Recommendations ranged from no suggested
methodology at all (Hubbard Farms, 1988-89, and Avian Farms
International, 1989) to extensive procedures by Ross Poultry
Breeders, Inc., (1986). The weighing techniques recommended
by Ross include individually weighing every bird in a
penned-up group (ca. 50 to 100 birds) every week from 4 wk
of age through peak production.
Generally, most primary breeders recommend that birds
be individually weighed weekly, starting at 4 or 5 wk of age


126
increased at a relatively more rapid rate and surpassed all
other average cost groups by 29 wk of age. At ca. 27 wk of
age AVC1/P, AVC2/P and AFC/P converged to a common value
indicating that the average total cost of rearing a pullet
(ATC/P) could be divided into ca. 33% for CHK, 33% for PFD
and 33% for the combined costs of PPAY, PSRV and PVAC.
The effect of feeding program on PFD through 30 wk of
age is depicted in Figure 6-2. All feeding programs
increased at parallel rates with proportionately lower
cumulative feed consumption values for the higher levels of
feed restriction. The resulting feeding program effect on
ATC/P was a proportional reduction in PFD costs at a common
age. However, the magnitude of this reduction was not as
great when PFD costs and ATC/P were calculated to a common
physiological age, i.e., 5% production.
Five percent production occurred atea. 24, 25, 26, 27
and 28 wk of age for the +8%, STD, -8%, -16% and -24%
feeding programs, respectively. When ATC/P for each feeding
program were evaluated to a common age (Table 6-3),
proportional decreases in ATC/P occurred. Even though
pullets were a common chronological age they were not the
same in terms of physiological development. For example,
pullets reared on the STD feeding program were at 5%
production at 25 wk of age and at an ATC/P of $5.834.
Pullets reared on the -24% program incurred a lower ATC/P of
$5.436 at 25 wk of age, but these pullets were 3 wk away


15
increased. Water consumption significantly increased as
dietary salt increased on feed days, but dietary salt did
not influence water consumption on the off-feed days.
Inherent differences in water consumption among strains of
breeders make water, litter and weighing management a
difficult task.
Feed and water management is also influenced by bird
behavior, which in turn can contribute to problems for the
weighing program. Murphy and Preston (1988) found that the
duration of eating and drinking among individuals was
variable.
Appleby et al. (1985) reported on a breeder hen
movement (ranging) study involving commercial flocks of ca.
4000 broiler breeders housed in deep litter. The study was
conducted intensively from 22 to 33 wk of age and then at
monthly intervals until 55 wk of age. They found that
closely restricted ranges did not occur in either sex.
Males had slightly larger ranges than females, but not
significantly so. There was no consistent change in the
area of the house used with age, and nesting was widely
distributed throughout the house. These findings were in
agreement with Craig and Guhl (1969) who reported that
individuals in flocks of chickens do not use space evenly
and that home ranges are either ill-defined or non-existent.


140
TABLE 6-6. Effect of feeding program on breeder hen average
cost budget through 40 weeks of production, calculated at
base prices and expressed as dollars per dozen hatching eggs
Feeding Program
+8% STD
-8%
-16%
-24%
Performance,, factors
Age, wk
64
65
66
67
68
Livability, %
*93
.93
.93
.93
.93
Feed,
kg/doz. H.E.
3.49
3.36
3.25
3,33
3.21
Hatching eggs,
doz/surv.
13.000
13.295
13.640
13,130
13,480
Average Fixed.... Costs
/DOZ. H.S. fAFC/El
Pullet
deprec., $
.442
.439
.435
.454
.445
Average Variable Costs / doz.
H.E,
fAVC/El
Feed, $
,436
.420
.406
.477
.401
Prod* pay, $
.300
.300
.300
.300
.300
Service &
supervision, $
.023
.023
,022
,023
.022
Average Total cost / doz. H.E.
(ATC/E)
$
1.201
1.181
1.161
1.193
1.169
Salvage adi ustment /, doz*,!LE
A.
Egg salv., $
Hen salv., $
.010
.083
.010
.079
.010
.075
.010
.075
.010
.073
Adjusted
ATC/E, $
1,109
1.092
1.076
1.108
1.087


31
The effectiveness of a lighting program is complicated
by the feeding program and by seasonal differences in
natural photoperiod and light intensity, out-of-season
flocks, i.e., those hatched January to May, experience
delayed sexual maturity and poorer reproductive performance.
Brake and Baughman (1989) studied the effect of light source
and intensity during rearing for both in- and out-of-season
flocks. They found that light intensity during the rearing
period may need to be somewhat lower than that of the laying
period in broiler breeders which are exposed to fall
(decreasing natural daylight) conditions during the early
phase of lay. These findings were consistent with data
presented by Morris (196?) suggesting that supplemental
light is most beneficial during fall and winter months of
lay.
Sexual Maturity
It is well known that restricting feed intake of
broiler breeder females during the rearing period will
retard growth and delay the onset of sexual maturity (Lee gt
al., 1971? Pym and Dillon, 1974; Watson, 1975; Leeson and
Summers, 1982). When changed from restricted feeding to
either an accelerated or ad libitum feeding program, various
degrees of compensatory growth can occur depending upon the
degree of restriction through the rearing period and the age
at the change. Brody et al. (1980) showed that after severe
feed restriction which delayed the onset of sexual maturity


93
have been shown to be significant and demonstrate a need to
understand these responses for each strain of bird
(Christmas and Harms, 1982; Cave, 1984b; Soller et_al.,
1984a; Anthony et al.. 1989). Furthermore, the ability to
manipulate the onset of sexual maturity through feed
restriction and diet composition (Soller et al., 1984b), and
by photostimulation (Morris, 1967; Brake and Baughman, 1989)
have proven to be important tools for the breeder manager.
The pullet-layer transition period has been identified
as a critical stage in developing efficient breeder hens
(McDaniel, 1983; Cave, 1984b; Brake et al.. 1985). Protein,
energy and mineral requirements are changing rapidly as body
development and sexual maturity are synchronized with age.
Targeting sexual maturity is therefore a synchronization
problem, where development of the skeleton, lean body
tissue, fat deposits and chronological age ideally converge
at a point that predisposes the breeder hen for an efficient
production cycle. These physiological changes manifest
themselves through various physical attributes that can be
quantified and possibly used as feedback information for the
manager regarding the feeding and lighting programs.
Therefore, the objective of this experiment was to
characterize how these physical attributes associated with
sexual maturity would be affected by severe feed
restriction, as the female broiler breeder passed through
the pullet-layer transition period.


47
means of two groups of observations were equal. The F-test
ratio of sample variance (Montgomery, 1984) was used to test
the hypothesis that the variance of two groups of
observations were equal. Differences between groups of
observations were considered significant if P < .05.
Results and Discussion
Experiment 1
Time of weighing. Initial body weights prior to
feeding on the first day were 2582 and 2676 g for Trial 1
and, 2747 and 2727 g for Trial 2 (Table 3-1). Change in
body weight (gain or loss) data from the pooled trials
(Table 3-1) demonstrate (Figure 3-1) how birds on the LTE
program reached a 205 g peak change in body weight in 3 h
after feeding, which was greater than the 155 g peak change
in the ERL program which also occurred at 4 h after feeding.
Birds on the LTE program lost weight, starting from peak
body weight and ending just prior to feeding, at the rate of
8.6 g/h while the rate for the ERL program was slower at 7.1
g/h. These differences in feeding programs suggest that
birds on a LTE program may require greater quantities of
water. The higher level of gain due to possible increased
water intake could explain the greater mass lost over this
time period. This finding also suggests that water
restriction should not begin for at least 4 h after birds
have finished eating.


155
program. The more restricted birds required less feed per
dozen hatching eggs than the standard.
The results indicate that feed restriction levels below
current recommendations can be used with broiler breeder
females without affecting fertility, hatchability, mortality
or average egg weight. The more severely restricted breeder
hen had a lighter mature body weight, smaller frame size and
consumed less feed without significantly reducing the number
of hatching eggs per hen-housed at 65 wk of age, when
compared to birds fed on a standard feeding program. The
implication of these results is that severe feed restriction
as a management technique can be utilized to maximize the
production of placeable chicks per hen housed while reducing
the cost of producing those chicks. This economic issue was
examined in Chapter VI.
Targeting Sexual Maturity
Under normal commercial pullet rearing conditions,
flock maturity occurs over a range of body weight X age
situations. This response is due to variation in
environmental, genetic, health, management and nutritional
factors. Furthermore, the nutritional requirements of the
maturing bird are increasing rapidly as the onset of egg
production occurs. Quantification of changes in the various
physical attributes associated with sexual maturity and
their use as feedback information for the breeder manager


HEN-DAY PRODUCTION, C?0
90
FIGURE 4-4. Effect of feed treatment on hen-day production
(%).


115
BODY YEISHT
TRT -oBg- A B ir~'v~~Â¥ C trr D 'ct-'tj FIGURE 5-9. Relationship of mean bursa weight (g) to body
weight (g) as affected by feed treatment (TRT a=+8%, B=STD,
C=-8% t D=-16% and E=-24%).


REFERENCES
Abplanalp, H., and D. C. Lowry, 1975. Selection for
increased incidence of double-yolked eggs in White
Leghorn chickens. Poultry Sci. 54:17-24.
Abplanalp, H., D. C. Lowry, and J. H. Van Middelkoop, 1977.
Selection for increased incidence of double-yolked eggs
in White Leghorn chickens. Br. Poult. Sci. 18:585-
595.
Anthony, N. B., E. A. Dunnington, and P. B. Siegel, 1989.
Egg production and egg composition of parental lines
and Fi and F2 crosses of White Rock chickens selected
for 56-day body weight. Poultry Sci. 68:27-36.
Appleby, M. C., S. N. Maguire, and H. E. McRae, 1985.
Movement by domestic fowl in commercial flocks.
Poultry Sci. 64:48-50.
Arbor Acres, 1985. Broiler breeder male and female feeding
and management guide. Glastonbury, CT.
Avian Farms International, Ltd., 1989. Male and female
parent breeder management guide. Glastonbury, CT.
Bartov, I., S. Bornstein, Y. Lev, M. Pines, and J.
Rosenberg, 1988. Feed restriction in broiler breeder
pullets: skip-a-day versus skip-two-days. Poultry Sci.
67:809-813.
Bennett, C. D., and S. Leeson, 1989a. Water usage in
broiler breeders. Poultry Sci. 68:617-621.
Bennett, C. D., and S. Leeson, 1989b. Growth of broiler
breeder pullets with skip-a-day versus daily feeding.
Poultry Sci. 68:836-838.
Bilgili, S. F., and J. A. Renden, 1985. Relationship of
body fat to fertility in broiler breeder hens. Poultry
Sci. 64:1394-1396.
Blair, R., 1972. Feed restriction in breeding birds.
Feedstuffs, Minneap., 44(10):36-39.
160


55
sacrificing an adequate level of accuracy for the decision
making process.
In summary, this study demonstrated that the required
balance between accuracy and efficiency of an appropriate
weighing program could be maintained if average body weight
and flock uniformity estimates were derived from one
convenient location, weighing all birds in a penned-up
sample, a number of penned-up samples with a total bird
count approximating at least one percent of the flock size,
and weighings conducted at the same time each weigh period.
Those elements of a comprehensive weighing program that
have the greatest impact on the level of accuracy of the
estimate, but do not add appreciably to the total cost of
data collection, e.g., time of weighing, should certainly be
given the greatest consideration.


100
feed restriction, at the levels used in this experiment, did
not alter the normal development of the bursa, fat pad,
pubic arch, comb or head score. Bursal involution was
significantly and negatively correlated with ovary
development (Table 5-1), suggesting that the bursa is
related to the onset of sexual maturity and thus not age
dependent. Feed restriction retarded, without altering, the
normal development and involution of the bursa (Table 5-3).
In summary, the main effect of feed restriction was to
delay the development of those attributes (investigated
here) associated with sexual maturity without significantly
altering their ultimate physiological values. The exception
to this finding was the effect of severe feed restriction on
shank length.


Sincere appreciation is expressed to the author's
parents, Mr. and Mrs. L. A. Fattori, for their support and
personal encouragement throughout the graduate program.
The author wishes to extend his deepest appreciation to
his wife Maisha for her care and support of their home and
family which freed the many hours needed to complete this
program. Without her patient understanding this endeavor
would have never been completed.
iii


25
54 weeks of age was significantly lower for caged than floor
housed hens.
Iggs from caged hens hatched significantly heavier
chicks than the floor housed counterparts which was
attributed to the difference in egg weight observed through
the laying period (Petitte et al., 1982). Measurements on
specific gravity were not reported in this study. Harms
ai* (1984a) found that specific gravity of eggs from hens
with access to litter was higher than hens housed on wire
floors, without a significant difference in egg weight.
They attributed this finding to increased intake of fecal
phosphorous, calcium and other nutrients important to egg
shell formation. Also, they reported that a decrease in
dietary calcium resulted in increased litter consumption.
It appears that caged broiler breeder hens produce larger
eggs with poorer shell quality that result in a concomitant
decrease in hatchability.
Pullet-haver Transition. Period
Bornstein and Lev (1982) discussed their view of the
changing nutritional needs of the bird through the pullet-
layer transition period in terms of flock dynamics. They
concluded, until nearly all the birds in a flock have
started to lay, average flock weights depend more on the
relative proportion within the flock of immature pullets,
prelaying pullets, and laying hens than on the weights of


95
scale to the nearest gram. Approximately 5 mL of blood was
obtained by cardiac puncture. Heparin was used as an
anticoagulant and blood samples were centrifuged at 1000 X G
for 10 min at room temperature. Total plasma lipid (LIPID)
was determined by the chloroform-methanol method (Folch et
al., 1957). Shank (tarsometatarsal) length (SHANK) was
measured with a Dekalb shank ruler to the nearest 1.0 mm;
pubic spread (distance between the pubic bones, ARCH) was
determined with a custom made ruler to the nearest 0.25 cm;
a subjective score of head development (comb and wattle
size, HEAD) ranging from 1 to 5, with 5 being the most
developed was recorded for each bird; and the height and
width of the comb (COMB) was combined into a comb factor
(cm'2) Four of those birds from each feed treatment were
killed (cervical dislocation) every 2 wk from 20 through 28
wk of age and the ovary (OVARY), oviduct (OVID), bursa of
Fabricius (BURSA), and abdominal fat pad (FTPD), including
the fat around the gizzard, were removed and weighed to the
nearest 0.1 g.
Statistical Analysis
Prior to analysis, absolute values for all physical
attributes measured were transformed to natural logarithms.
Data expressed as a percent of live body weight were
transformed to arc sine square roots (Gomez and Gomez,
1984), and then all data were subjected to analysis of
variance by using the linear statistical model for a


97
feed treatment are discernable at any age and significance
among these differences are presented in Tables 5-2 and 5-4.
The attributes measured in this experiment were
classified as those increasing linearly with age, i.e.,
ARCH, BWT, COMB, FTPD, HEAD, and SHANK, and those that
abruptly increase near sexual maturity, i.e., LIPID, OVID,
and OVARY. The BURSA (Figure 5-9) was a special case that
was characterized by a quadratic response to aging with a
relatively rapid regression in absolute weight upon sexual
maturity. The effect of feed treatment on the development
of each attribute could be characterized by a delay,
relative to age, in the development of that attribute. The
effect relative to body weight was only apparent in the most
severe levels of restriction, i.e., -16% and -24%, where
development of individual attributes stabilized at lower
body weights. This observation can be explained by the
significant reduction in shank length for birds on the -16%
and -24% feed treatments. The severe feed restriction
retarded skeletal growth (frame size, Table 5-1) which
resulted in lowered body weights at sexual maturity. This
finding was similar to that of Leeson and Summers (1984) and
Brody et al. (1980).
The relationship between feed treatment and shank
length over the life cycle of the breeder hen is depicted in
Figure 5-10. These data demonstrate that: first, increasing
the levels of feed restriction had significant proportional


ACKNOWLEDGMENTS
The author wishes to express his most sincere
appreciation to his co-advisors, Dr. Henry R. Wilson and Dr.
Peter E. Hildebrand, for their guidance throughout the
author's Doctor of Philosophy program. Their strong
direction and support of the selected coursework and
research program enabled an understanding of a broad range
of issues important to poultry management.
Special appreciation is extended to other committee
members, Dr. Steve A. Ford, Dr. R. H. Harms, and Dr. F. Ben
Mather, for their encouragement, technical advisement and
guidance throughout the research program.
Additional gratitude is extended to the professors of
the University of Florida Poultry Science Department, Mr.
David P. Eberst, Mr. W. Gary Smith and the farm crew, and
all members of the staff for their assistance in faciliting
the work load over a long research period.
The author is also indebted to Mr. Harold Barnes and
Gold Kist, Inc. for the cooperation and assistance in
conducting research on-farm and whose advice was of great
value.
ii


120
7) estimate the change in breeder hen laying cost structure
resulting from increased pullet rearing density.
Materialsand Methods
This analysis utilized experimental data (feed
consumption, body weight and hatching egg production)
obtained from a broiler breeder female feed restriction
experiment (Chapter IV) which formed the basis of the
biological response to severe feed restriction. The five
feeding programs used in this experiment were: 8 percent
above the breeder recommendations (+8%); standard (STD)
which approximated the breeder's guidelines? and severe feed
restriction of 8 (-8%), 16 (-16%) and 24 (-24%) percent
below standard.
The broiler breeder life cycle was divided into two
distinct accounting periods. The pullet rearing period
began at one day of age and ended at 5% production. The
breeder hen laying period began at 5% production and
continued until flock liquidation.
Mortality, and.Culling
Since the results of the feed restriction experiment
indicated no significant differences in either rearing or
laying period mortality due to feed treatment, the
assumption was made that cumulative mortality progressed at
a linear rate for both pullets and breeder hens. Pullet
mortality and culling during rearing (PMRT) was established


153
Feeding Programs
In order for the breeder manager to maximize the number
of placeable chicks from a breeder rearing and laying
program, he must manage the feeding program so the average
body weight of a flock follows a growth curve established
for a particular strain. The overall objective of Chapter
IV was to evaluate the breeder's recommended growth curve by
comparing their standard growth curve with curves resulting
from severe feed restriction.
Proportional increases in the level of feed restriction
resulted in corresponding decreases in mean body weight for
the more restricted birds. The resulting growth curves for
the severely restricted birds paralleled the standard growth
curve, which was itself a good approximation of the
breeder's recommended growth curve. Feed restriction 16%
and 24% below standard permanently stunted the frame size
and reduced adult body weight of the breeders. Despite the
severity of restriction, there were no differences in either
pullet or breeder hen mortality, or in flock uniformity
among feed treatments. There appeared, however, to be a
trend towards increased mortality for the most restricted
birds.
Severe feed restriction significantly delayed flock
sexual maturity (age at 50% production) by ca. 1 wk for
every 8% restriction below standard. Average hen-day
production to the common age of 65 wk was significantly


156
during the pullet-layer transition period would make it
possible for the feeding and lighting programs to be more
properly adjusted to the changing needs of the flock at the
appropriate age.
The objective of Chapter V was to characterize how
these physical attributes associated with sexual maturity
would be affected by severe feed restriction as female
broiler breeders passed through the pullet-layer transition
period.
The various physical attributes measured were
classified as those increasing linearly with age, i.e.,
pubic spread, body and fat pad weight, comb development,
head score (comb and wattle appearance) and shank length,
and those that abruptly increased near sexual maturity,
i.e., total plasma lipid concentrations, and oviduct and
ovary weights. The bursa of Fabricius was a special case
that increased with age and body weight then regressed upon
sexual maturity.
The generalized effect of feed restriction on these
attributes was to delay their development without altering
their ultimate physiological values. The exceptions to this
finding were relative body weight and shank length after
maturity. The most severe feed restricted birds had reduced
skeletal size and body weight.
This study demonstrated that the breeder manager could
use measurements of the comb, pubic arch or a subjective


16E
Lilburn, M. S., K. Ngiam-Rilling, and J. H. Smith, 1987.
Relationship between dietary protein, dietary energy,
rearing environment, and nutrient utilization by
broiler breeder pullets. Poultry Sci. 66:1111-1118.
Lilburn, M. S., K. Rilling, F. Mack, E. 0. Mills, and J. H.
Smith, 1986. Growth and development of broiler
breeders. 1. Effect of early plane of nutrition and
growth rate. Poultry Sci. 65:1070-1075.
Lott, B. D., F. N. Reece, and J. L. McNaughton, 1982. An
automated weighing system for use in poultry research.
Poultry Sci. 61:236-238.
Lowry, D. C., and H. Abplanalp, 1967. Selection for an
increase in multiple ovulation in the chicken.
Genetics 56:573-574.
Lowry, D. C., J. C. Dobbs, and H. Abplanalp, 1979. Yolk
deposition in eggs of a line selected for simultaneous
multiple ovulation. Poultry Sci. 58:498-501.
Luther, L. W., W. W. Abbott, and J. R. Couch, 1976. Low
lysine, low protein, and skip-a-day restriction of
summer and winter reared broiler breeder pullets.
Poultry Sci. 55:2240-2247.
May, J. D., S. L. Branton, J. W. Deaton, and J. D. Simmons,
1988. Effect of environmental temperature and feeding
regimen on quantity of digestive tract content of
broilers. Poultry Sci. 67:64-71.
McDaniel, G. R., 1974. The production of broiler hatching
eggs in cages. Poultry Sci. 53:1954.
McDaniel, G. R., 1983. Factors affecting broiler breeder
performance. 5. Effects of preproduction feeding
regimens on reproductive performance. Poultry Sci.
62:1949-1953.
McDaniel, G. R., J. Brake, and R. D. Bushong, 1981a.
Factors affecting broiler breeder performance. 1.
Relationship of daily feed intake level to reproductive
performance of pullets. Poultry Sci. 60:307-312.
McDaniel, G. R., J. Brake, and M. K. Eckman, 1981b. Factors
affecting broiler breeder performance. 4. The
interrelationship of some reproductive traits.
Sci. 60:1792-1797.
Poultry


151
Weighing Programs
Accurate and timely body weight estimates from an on-
farm weighing program enable the breeder manager to make
effective decisions concerning the proper quantity and
quality of feed to allocate to a flock. This body weight
information is an estimate of the flock's growth and
development response to environmental, genetic, health,
management and nutritional conditions. Variation in these
factors cause the decision making process to be a complex
task. Since body weight estimates are the basis for the
decision making process, any error in their estimates will
be reflected in the inefficient use of resources in the
rearing and production of a flock.
The overall objective of Chapter III was to establish
general guidelines for the development and implementation of
an appropriate weighing program. The study examined the
effect of scale type, sample units, sample size, sample
location, time of sampling, and complexity of procedures
used in estimating body weight, body weight gain and flock
uniformity.
It was found that a spring scale was as accurate as an
electronic scale in estimating average body weight, although
the printer feature of some electronic scales would probably
reduce transcription errors. Weighing birds individually
was found to be a better procedure than group weighing when
accurate estimates of flock uniformity are desired. A


68
severe feed restriction (relative to breeder
recommendations) and subsequent effects on the more specific
evaluation criteria: body weight, sexual maturity, mortality
and other hatching egg production parameters that impact on
the production of placeable chicks per hen housed.
Materials and Methods
Stock and Management
Male and female Arbor Acres strain broiler breeders,
hatched in-season at a commercial hatchery (September, 1987)
and vaccinated for Marek's disease before placement were
used in this experiment. A total of 860 day-old female
chicks were randomly placed into 20 litter-floor pens of an
open-sided house, Each 3.1 X 3,6 m pen was equipped with an
automatic waterer for ad libitum drinking and three pan type
feeders. Male chicks were group reared separately in a
litter-floor pen of an open sided-house and fed according to
breeder recommendations. At 20 wk of age all males were
individually weighed and 60 males, weighing between 2650 and
2950 g, were randomly placed 3 per female pen. sixty
replacement males (12 per treatment) were randomly placed in
pens in a separate house and maintained on respective feed
treatments. All birds were beak trimmed and vaccinated for
fowl pox at 10 d of age. Birds were vaccinated for
Newcastle disease and infectious bronchitis at 2, 5, 12, and
15 wk of age, and avian encephalomyletitis and fowl pox at


TABLE 4-
various
8. Cumulative
chronological
feed, crude protein and metabolizable energy
and physiological ages by feed treatment
intake per
bird at
Feeding program
+8%
STD
-8%
-16%
-24%
Chronoloaical age
20 wk
Feed, Kg
8.94
8.32
7.71
7.09
6.49
CP, Kg
1.38
1.29
1.20
1.10
1.01
ME, Meal
27.70
25.78
23.86
21.95
20.07
35 wk
Feed, Kg
25.55
24.03
22.63
20.94
19.28
CP, Kg
3.77
3.54
3.33
3.08
2.83
ME, Meal
76.63
72.07
67.88
62.81
57.85
65 wk
Feed, Kg
57.52
55.93
54.49
52.64
50.91
CP, Kg
8.18
7.94
7.74
7.48
7.23
ME, Meal
171.71
166.98
162.63
157.01
151.82
Physiological age
Rearing
phase, d
175
179
184
187
194
Pullet
Feed, Kg
13.22
12.73
12.58
12.35
12.05
CP, Kg
2.08
2.01
1.99
1.96
1.91
ME, Meal
39.71
38.20
37.64
36.85
35.90
Breeder
Feed, Kg
44.31
43.19
41.91
40.29
38.86
CP, Kg
6.10
5.93
5.75
5.52
5.32
ME, Meal
132.00
128.78
124.99
120.16
115.92
Life of
flock
FEED/DZHE, Kg
3.94
3.92
3.81
3.82
3.59
CO


52
Tables 3-4 and 3-5, which are evaluated and presented in
Table 3-6. First, the measurement of average body weight
gain of the pullets decreased by ca. 10 g/h between the AM
and PM weighings, despite the fact they were off feed. This
was determined from Table 3-6 where the difference in pullet
body weight from AM to PM at 10 wk (Trial 1) ranged from a
loss of 43 g to 67 g over the 4 h period. Secondly, average
body weight gain data for the adult breeder hens were not as
conclusive. Birds in the FDD location gained weight over
the two week period in both Trial 1 (66 and 77 g) and Trial
2 (141 and 142 g), however they lost weight (-8 and -35 g)
between the AM and PM weighings in Trial 1. This was in
marked contrast to birds weighed at the END location which
lost considerable weight (-141 and -159 g) over the two week
period but gained back nearly 25-30% of it (36 and 60 g)
between the AM and PM trials. The principal conclusion
being that flock dynamics in the breeder house contribute to
a complex situation where relatively radical changes in body
weight occur throughout the day. This is especially true
during the morning hours when feeding, drinking and laying
are all contributing to variation in body weights.
Outliers. Information required to determine if a
grossly under- or overweight bird should be rejected as a
true outlier to the normal body weight distribution is
presented in Table 3-7. No true outliers were detected in
the straight run broiler flocks. Half of the suspected


69
10 wk of age. Chicks were reared under natural daylight
conditions until 20 wk of age, then daylength was abruptly
increased from ca. 12 h to 15 h by supplementing with
incandescent light, ca. 22 lux at bird level, from 0430 h to
1930 h, E.S.T.
Feed Treatments
Birds were fed ad libitum until 2 wk of age and
restricted daily during the third week on a starter diet
(Table 4-1). All birds were fed on a skip-a-day basis a 16%
grower diet from 4 through 8 wk, a 12% grower diet from 9
through 15 wk, and a 16% grower diet from 16 through 19 wk
of age. Five feed treatment groups based on a standard
feeding program were used. The feed treatments were
designed to have body weight follow growth curves over the
life cycle that were: 8 percent above the breeder
recommended standard curve (+8%); standard (STD), which
approximated the breeder's standard curve; and 8 (-8%), 16
(-16%) and 24 (-24%) percent below the standard curve. Feed
allocations for the STD treatment were derived from average
weekly body weight estimates and all other feed treatments
adjusted quantitatively. Daily feeding of a laying diet
began at 20 wk of age, where the nutrient intake, other than
energy provided per bird per day, was based on current
recommendations (Wilson and Harms, 1984). This intake
furnished for the STD treatment 20.6 g protein, 754 mg
sulfur amino acids, 4.07 g Ca, 683 mg total P, and 170 mg


42
processing plant. A weighing program is considered
appropriate for a particular attribute (mean body weight and
flock uniformity) in a particular field condition
(restricted or full fed) if it satisfies several conditions.
First, the accuracy of the estimated attribute must be as
good as, or better than, a level required to achieve an
objective. The objective in this case is to determine the
best nutrient allocation or other management decision
necessary to achieve body weight and uniformity standards.
Secondly, the cost of conducting a weighing program must be
within the practical limits of resources available.
A review of the various management guides published by
the breeder companies confirms the lack of consensus
concerning suggested weighing procedures. Recommendations
range from weighing 1, 2, or 3% of the flock to sampling 2,
3, or 4 locations in a house. Furthermore, none of the
management guides quantify for the breeder manager what
level of technical or economic inefficiency will result if
the procedures are not followed.
There has been little or no research conducted on
weighing procedures that maintain a practical level of
accuracy of the weigh data while minimizing the cost of
collecting those data.
The objective of this study was to establish general
guidelines for the development and implementation of an
appropriate weighing program. Specifically, the objectives


COMB
111
2.5
28
O
= +8* 0= STD £= -8* -16% 0= -24%
_2
FIGURE 5-5. Effect of feed treatment on comb factor (cm )
with respect to age (wk) and body weight (g)


65
FIGURE 3-3. Frequency distribution of confidence intervals for
a fixed quantity of birds excluding outliers (A) and all birds
penned-up in a flock (B)


5-4 Effect of feed treatment on head score (no.,
5=most developed) with respect to age (wk) and
body weight (g) HO
5-5 Effect of feed treatment on comb factor (cm'2)
with respect to age (wk) and body weight (g) m
5-6 Effect of feed treatment on plasma total lipid
(mg/mL) with respect to age (wk) and
body weight (g) 112
5-7 Effect of feed treatment on oviduct weight (g)
with respect to age (wk) and body weight (g)..... 113
5-8 Effect of feed treatment on ovary weight (g)
with respect to age (wk) and body weight (g) 114
5-9 Relationship of mean bursa, weight (g) to body
weight (g) as affected by feed treatment
(TRT A=+8%, B=STD, C=-8%, D=-16%, and E=-24%).... 115
5-10 Effect of feed treatment on shank length (mm)
with age (wk) 116
6-1 Average cost structure of a standard pullet
rearing program, at base prices 143
6-2 Average cumulative feed cost for various
pullet feeding programs 143
6-3 Sensitivity of pullet average total cost to
changes in component costs at 20, 25, and 30
weeks of age for the STD feeding program
(CHK=chick, PFD=pullet feed, PPAY=grower pay,
PMRT=pullet mortality, DENSITY=pullet housing
density) 144
6-4 Sensitivity of pullet average total cost to
changes in component costs at 20, 25, and 30
weeks of age for the -24% feeding program 145
6-5 Effect of a 20% change in component costs on
average total cost per pullet survivor at 5%
production 146
6-6 Average total cost of a dozen hatching eggs for
the STD and -24% feeding programs, with age 146
x


o= +8% 0= STD # = -8 5! <2= -16% 0= -2 4%
FIGURE 5-4. The effect of feed
5=most developed) with respect
(g)
treatment on head score (no.,
to age (wk) and body weight


75
Production Performance
The average hen-day production response to feed
treatment is illustrated in Figure 4-4. Generally, there
was a delay in sexual maturity which was proportional to the
level of feed restriction. The -16% and -24% feed
treatments had a slower rise to peak production, perhaps due
to poorer flock uniformity at that time. The production
response to all feed treatments peaked at ca. 82 to 84% and
the most restricted birds (-24%) remained at higher levels
of production from 40 through 65 weeks of age.
Average hen-day production to the common age of 64 wk
was significantly lower for the -16% and -24% treatments
(Table 4-4). These treatments were in production 8 and 15
days less than STD, respectively. However, at 64 wk of age
the -24% treatment was still at 63.4% production which was
11.5% higher than STD and represented the level of
production of STD some 10 wk earlier. This implies that
production would be likely to continue at acceptable levels
to industry for several more weeks. Moreover, there was no
significant difference in mean hen-housed production between
the -24% and STD treatments to 64 wk of age. Although
mortality was not affected by treatment the timing of
mortality relative to the production cycle was a
contributing factor to there not being differences in hen-
housed production.


118
consequences of these effects are rarely determined.
Proudfoot and Lamoreaux (1973) compared "monetary returns"
resulting from full feeding, restricted feeding (75% of full
feed) and full feeding low protein diets (12.3%) during the
rearing period, as well as feed restriction during the
laying period of different meat-type strains. They found
that feed treatments used during the rearing period had a
significant effect on "monetary returns" from hatching egg
production with the restricted feeding program resulting in
higher monetary gains. The adult breeder feed treatment
(full fed vs. 90% of full fed) exhibited no significant
effect on either revenues or monetary returns over costs.
Proudfoot et al. (1984) evaluated the economic effect
of feed restriction during the laying period on the
performance of dwarf and normal broiler breeder hens.
"Monetary returns" calculated per hen housed showed that
normal breeder hens had significantly higher returns than
dwarf breeders. This was true despite a significantly lower
dwarf breeder level of feed consumption per dozen hatching
eggs produced. No difference in returns due to a level of
feed restriction 5% below standard could be detected. These
authors noted that because dwarf females can be housed more
densely than normal females, fixed costs of production could
be less per bird and may provide greater total returns to
the hatching egg producer than normal broiler breeder
strains housed at lower densities.


164
Ingram, D. R., and H. R. Wilson, 1987. Ad libitum feeding
of broiler breeders prior to peak egg production.
Nutr. Rept. Int. 36:839-845.
Ingram, D. R., and H. R. Wilson, and F. B. Mather, 1988.
Influence of lighting program and rate of body weight
gain on sexual maturity and performance of broiler
breeders. Nutr. Rept. Int. 38:29-35.
Jaap, R. G., 1955. Sampling body weight of growing
chickens. Poultry Sci. 34:396-397.
Katanbaf, M. N., E. A. Dunnington, and P. B. Siegel, 1989a.
Restricted feeding in early and late-feathering
chickens. 1. Growth and physiological response.
Poultry Sci. 68:344-351.
Katanbaf, M. N., E. A. Dunnington, and P. B. Siegel, 1989b.
Restricted feeding in early and late-feathering
chickens. 2. Reproductive response. Poultry Sci.
68:352-358.
Katanbaf, M. N., E. A. Dunnington, and P. B. Siegel, 1989c.
Restricted feeding in early and late-feathering
chickens. 3. Organ size and carcass composition.
Poultry Sci. 68:359-368.
Lavie, D., 1988. Imprinting offers possibilities for
broiler chicks. Poultry-Misset Int. 4(5):17-19.
Lee, P. J. W., A. L. Gulliver, and T. R. Morris, 1971. A
quantitative analysis of the literature concerning the
restricted feeding of growing pullets. Br. Poult. Sci.
12:413-437.
Leeson, S., and J. D. Summers, 1983. Consequence of
increased feed allowance for growing broiler breeder
pullets as a means of stimulating early maturity.
Poultry Sci. 62:6-11.
Leeson, S., and J. D. Summers, 1984. Influence of
nutritional modification on skeletal size of Leghorn
and broiler breeder pullets. Poultry Sci. 63:1222-
1228.
Leeson, S., and J. D. Summers, 1985. Effect of caged versus
floor rearing and skip-a-day versus every-day feed
restriction on performance of dwarf broiler breeders
and their offspring. Poultry Sci. 64:1742-1749.


CHAPTER IV
THE EFFECT OF SEVERE FEED RESTRICTION
DURING THE REARING PERIOD ON FEMALE
BROILER BREEDER REPRODUCTIVE PERFORMANCE
Introduction
Early studies that examined the effect of feed
restriction on reproductive performance utilized ad libitum
feeding as the bench mark or control group in their
experimental designs. A generalized model illustrating this
effect was proposed by Bullock et al. (1963), where they
postulated that the only response to restricted feeding is a
delay in sexual maturity, characterized by the displacement
or shifting of the production curve to older ages. Since
then, numerous research projects have shown that relative to
ad libitum controls, feeding programs that restrict the feed
intake of broiler breeder females during rearing will delay
sexual maturity (Lee et al.. 1971; Harms et al.. 1979;
Leeson and Summers, 1982), increase initial egg size (Blair
et al.. 1976; Leeson and Summers, 1982), decrease the number
of doubled-yolked eggs and therefore increase the number of
settable eggs (Fuller et al.. 1969; Chaney and Fuller, 1975;
Christmas and Harms, 1982; Hocking et al.. 1989; Katanbaf et
66


12
and continued through peak production. All birds in a
pernied-up group should be weighed and the weighings should
consistently occur on the off-feed day, at the same time
(afternoon) and at the same locations in the house.
Variation in the number of locations to use in a house range
from 2 to 5 depending upon the company. For example,
Peterson Farms (1988) recommends weighing a minimum of 2% of
the females and 5% of the males each week from 3 wk through
peak production, every two weeks up to 48 wk of age and
monthly thereafter. They suggest group weighing from 3
through 4 wk of age and then individual weighing from 5 wk
on. Sampling should be random and as consistent as
possible. Weigh all birds penned from 4-5 locations in the
house on the off-feed days. Weigh at the same time each
weighing and use the same scale.
The only recent publication found on weighing
methodology was by Harms et al. (1984b), This study was
conducted to develop a method for weighing egg-type pullets
that would be faster, more accurate, and more informative
than previous procedures* They concluded that weighing
replacement pullets in groups of 5 was just as good as
weighing individual birds* The average weight was the same
if all birds penned were weighed. They utilized a 95%
confidence limit to determine whether the birds differed
significantly from a desired target body weight. They also
used the bird-to-bird standard deviation to provide a


99
the ARCH compared to the more abrupt change in correlation
significance of COMB and HEAD.
Bornstein et al. (1984) reported a high correlation
(r=,91) between abdominal fat and mean body weight at first
egg. The present study demonstrated that such levels of
correlation can exist even prior to sexual maturity and
possibly a decrease in correlation may occur as other
attributes (OVID, OVARY, COMB) increase their percentage of
relative body weight.
The primary focus of this study was the comparison of
the STD feed treatment to the most severe level of feed
restriction (-24%). Significant differences in BWT for
these two treatments at each age were expected and observed
(Tables 5-2 and 5-4). Furthermore, those attributes
exhibiting linear increases with age were all significantly
different at a common age, between these two treatments.
Attributes associated with an abrupt increase in absolute
values varied with age. Generally, at early ages, i.e., 20,
22, and 24 wk of age, no significant differences were found
in OVARY, OVID and LIPID values, but as sexual maturity
initiated there were significant differences in these
attributes.
Difficulty in establishing clear-cut trends in
attribute development were due to high variability and small
sample sizes for those attributes obtained from sacrificed
birds (Table 5-3 and 5-4). However, it appears that severe


Introduction................................ 66
Materials and Methods. 68
Results and Discussion. 72
VCHARACTERIZING THE ONSET OF SEXUAL MATURITY
IN FEED RESTRICTED BROILER BREEDER FEMALES.. 92
Introduction 92
Materials and Methods. 94
Results and Discussion...................... 96
VIECONOMIC ANALYSIS OF SEVERE FEED
RESTRICTION ON BROILER BREEDER PULLET
REARING AND BREEDER HATCHING EGG PRODUCTION. 117
Introduction.117
Materials and Methods 120
Results and Discussion. 125
VIISUMMARY AND CONCLUSIONS. ISO
Weighing Programs........................... 151
Feeding Programs 153
Targeting Sexual Maturity................... 155
Economic Analysis of Feeding Programs....... 157
REFERENCES. 160
BIOGRAPHICAL SKETCH. 171


94
Materials and Methods
Stock. Management, Feed Treatments
Detailed descriptions of the strain, management
procedures and feed treatments have been presented (Chapter
IV). Briefly, 860 Arbor Acres strain of broiler breeder
chicks (hatched September, 1987) were reared in 20 litter-
floor pens of an open-sided house. Chicks were reared under
natural daylight conditions until 20 wk of age then
daylength was abruptly increased to 15 h by supplementing
with incandescent light from 0430 h to 1930 h, E.S.T.
Birds were fed ad libitum until 2 wk of age and
restricted daily during the third wk on a 21% starter diet.
All birds were fed on a skip-a-day basis a 16% grower diet
wk 4 through 8, a 12% grower diet wk 9 through 15, and a 16%
grower diet wk 16 through 20. After 20 wk of age all birds
were fed a breeder diet on a daily basis. Five feed
treatments based on a standard feeding program were designed
to follow growth curves that were; 8 percent above the
breeder standard (+8%) ,* standard (STD), which approximated
the breeder's standard curve; and 8 (-8%), 16 (-16%), and 24
(-24%) percent below standard.
Reproduction Traits Measured
Eighty females were randomly sampled every 2 wk from 16
through 28 wk of age and measurements on various physical
attributes made. Sixteen birds per treatment were
identified and weighed individually (BWT) on an electronic


147
PRICE SITUATIONS
FIGURE 6-7. Sensitivity of breeder hen average total cost to
changes in feed costs (BFD) or costs due to breeder hen
mortality (BMRT) at 40 weeks of production for the STD and
-24% feeding programs.


Table 4-6. Effect of feed treatment on mean (+ SEM) specific gravity (SG) and egg weight
(EW), and the correlation between these parameters at various ages
Feeding program
Corr.
Age, +8% STD -8% -16% -24% Pooled Coef.
(wk) /Prob
30/SG
1.0812
+
.0005
1.0824
£
.0004
1.0820
£
.0005
^ab
1.0814
+
,0g04
1.0812
+
,0g08
1.0816
+
.0002
.262
30/EW
58.2
£
.6
58.2
£
.5
56.6
£
55.7
£
55.3
£
56.8
£
.4
.264
34/SG
1.0812
£
,0008b
1.0810
£
.0004b
1.0832
£
,0g03
1.0846
£
.0004
5b c
1.0837
£
.0004
1.0827
+
.0003
-.691
34/EW
63.4
£
.6
61.4
£
. 5b
60.5
£
59.9
£
58.9
£
.2
60.8
£
.4
.001
38/SG
38/EW
1.0780
66.0
1
£
.0005b
.6
1.0777
65.5
£
£
.0004b
^ab
1.0786
64.4
£
£
.0007b
2bc
1.0793
64.7
£
£
,0003b
6b
1.0805
63.0
£
£
.0005
. 4c
1.0788
64.7
£
£
.0003
.3
-.512
.021
42/SG
42/EW
1.0741
65.6
£
£
,0008b
.6
1.0744
65.8
£
£
,0007b
.8
1.0751
64.8
£
£
.0004b
.6
1.0764
65.1
£
£
.0002
.6
1.0766
64.0
£
£
.0006
.2
1.0753
65.1
£
£
.0003
.3
-.600
.005
46/SG
46/EW
1.0775
68.3
£
£
,0007b
.2
1.0773
66.9
£
£
,0004b
6b
1.0781
66.1
£
£
.0003b
^bc
1.0782
65.4
£
£
.0007b
6bc
1.0798
65.1
£
£
.0009
. 7
1.0782
67.0
£
£
.0003
.4
-.386
.093
50/SG
50/EW
1.0747
67.7
£
£
,0006b
.7
1.0752
67.6
£
£
0009b
.9
1.0750
66.9
£
£
.0006b
1.1
1.0782
66.9
£
£
.0005
.8
1.0771
65.7
£
£
. 0012b
.7
1.0760
66.3
£
£
.0003
.3
-.043
.856
54/SG
54/EW
1.0768
69.4
£
£
.0004
.4
1.0760
68.4
£
£
.0005
^ab
1.0758
67.8
£
£
.0003
8ab
1.0777
68.3
+
£ 1,
.0010a
,0a6
1.0775
66.8
£
£
.0005
. 6b
1.0767
68.1
£
£
.0003
.3
-.181
.444
58/SG
58/EW
1.0777
70.3
£
£
.0005
.3
1.0782
70.2
£
£
.0006
.2
1.0783
69.1
£
£
.0002
1.0
1.0790
69.2
£
£
.0008
.8
1.0788
69.1
£
£
.0010
.4
1.0784
69.6
£
£
.0003
.3
-.263
.263
62/SG
1.0785
+
.0008
1.0786
£
.0004
1.0786
+
.0004
1.0797
+
.0008
1.0798
+
.0011
1.0790
+
.0003
-.322
62/EW
72.5
£
.3
71.3
£
.6
71.4
£
1.0
71.2
£
.1
70.7
£
.5
71.4
£
.3
.166
Pooled
.000515
.7
/SG
/EW
1.0777
66.8
£
£
.0004b
.7
1.0779
66.1
£
£
,0004b
.7
1.0783
65.3
£
£
1.0794
65.2
£
£
.0004
.8
1.0794
64.3
£
£
.0004
.8
1.0785
65.0
£
£
0
.2
-.528
0
Corr.
coef. -.41 -.542 -.593 -.523 -.453
Prob .007 .001 0 .001 .006
ab Means within a row having no common superscript are significantly different (P < .05).
Corr. coef.= Pearson's product-moment correlation coefficient and probabilities of significance in parenthesis.
co
ui


TABLE 3-5. Effect of sample location (FDD vs. END) at
various ages and by sample type (PHD vs. FXD) on mean
breeder hen body weight and uniformity (SD), (Exp. 3).
Sample
TRIAL 1
~>} *
TRIAL
2
Age/Time
type
FDD
END
Sig.
FDD
END
Sig.
36 wk/AM
PND
1 no.
69
69
77
70
mean, g
3291
3387
**
3342
3388
NS
SD, g
241
268
NS2
310
326
NS
FXD
N no.
60
60
60
60
mean, g
3296
3385
*
3337
3412
NS
SD, g
252
261
NS
295
330
NS
38 wk\AM
PND
N no.
64
64
64
64
-
mean, g
3356
3245
*
3482
3403
NS
SD, g
356
300
NS
326
292
NS
FXD
n no.
60
60
60
60
mean, g
3373
3240
NS
3478
3395
*
SD, g
356
300
NS
362
298
NS
38 wk\PM
PND
N no.
62
62
mean, g
3348
3281
ms
X-
sd, g
320
268
NS
FXD
N no.
60
60
mean, g
3338
3286
NS
SD, g
321
271
NS
*t-test on sample means (P<.05).
aF-test ratio on sample variance FDD Feed dump location SD= standard deviation
END End location Sig= significance (P&.05)
PND All birds penned
FXD Fixed quantity


TABLE 4-5. Effect of feed treatment on hen-day production for chronological and
physiological ages
Chronological
age
Physiological age*
Age
(wk)
+8%
STD
-8%
-16%
-24%
Week
Prd.
+8%
STD
-8%
-16%
-24
%
25
1.7a
8b
jbc
^bc
0C
1
10
.5a
9
43b
7.2bc
5.5
7
. obc
26
11.3a
6.
5b
3
.1
. 8d
0d
2
33
.9a
26
. 6b
14.7cd
13.8d
18
.7
27
36.3a
21.
9b
9
. 8
3
. 8d
1.0d
3
58,
.5a
47,
.0b
31.5C
26.3d
33,
. 8C
28
58.5a
42.
lb
23
. 5C
10
. 7d
4.3
4
72,
.0a
67,
.Ia
49. lb
38.1
50,
.lb
29
72.9a
62.
lb
38
.7
21
. 5d
11.4e
5
78,
.6a
75,
.7a
65.5b
50.6
63
.lb
30
79.4a
73.
lb
55
.5
35
. 3d
25.3a
6
81.
,1a
82,
,1a
72.4b
64.7C
68,
. 6bc
31
81.8a
81.
Ia
66
. 6b
45,
.3
40.8d
7
83.
,4a
82.
,2a
80.1a
75.2b
73,
,0b
32
84.1a
83.
5a
76.
. 6b
59,
. 8
57.5C
8
83.
4ab
84.
,4a
85.3a
80.2bc
78,
. 6
33
83.4a
82.
7a
81,
,5a
71,
. 6b
64.9C
9
82.
,4a
83.
,0a
82.8a
82.3a
81,
,4a
34
82.1a
83.
8a
82.
,7a
78.
,0b
71.6C
10
81.
,2a
80.
,6a
82.8a
83.6a
83.
,3a
35
81.6a
80.
4a
82.
,9a
82.
,6a
75.8
11
82.
,1a
83.
,1a
85.4a
82.1a
85.
,5a
36
81.3bc
82.
9b
85.
,6a
82.
. 7b
80.0C
12
79.
, 4b
83.
,4a
84.9a
84.9a
84.
,1a
37
79.8b
82.
9a
83.
,8a
83.
,0a
81.9ab
13
77.
, 9b
79.
48b
83.1a
80.3ab
82.
,8a
38
77.0
80.
7b
84.
,0a
83.
,3a
84.5a
14
76.
,2b
78.
4b
81.9a
80.5a
80.
,5a
39
76.2b
77.
5b
83.
,0a
82.
,6a
84.1a
15
75.
.3a
77.
,5a
78.1a
76.1a
75.
,9a
40
75.4C
79.
lb
79.
. 6b
78.
,9b
84.6a
16
72.
.5a
73.
,3a
75.8a
71.6a
74,
,5a
41
72.0d
74.
6C
77.
,0b
79.
,6a
81.7a
17
69.
4bo
67,
,0C
70.9abc
73.2ab
74.
,6a
42
68.0
67.
8C
73.
. 9b
72.
,3b
77.8a
18
62.
, 8b
68.
yab
73.9a
62.2b
72.
,3a
43
63.5d
68.
8
72.
,0b
73.
j^ab
75.7a
19
62.
,9b
71.
,0a
72.5a
60.3b
71.
,0a
44
64.0
67.
9b
71.
,1a
71.
,5a
74.1a
20
62.
. 7b
67.
,6a
69.8a
67. lab
70.
,3a
54
62. lb
61.
lb
65.
,3a
66.
,4a
65.8a
30
62.
l^be
60.
, 8C
66.2b
65.9bc
71.
,1a
64
54.3C
51.
, 9C
58.
. 7b
59.
, 3b
63.4a
35
59.
2ab
58.
. 5b
61.8ab
60.5ab
63,
,9a
Avg.
63.5a
63.
,1a
63.
,3a
61.
,0b
61.0a
Avg.
66.
,1a
66,
,3a
66.5a
64.7b
66,
,9a
Determined by adjusting the first day of 5% production for each rep. to be the start of the production
cycle.
a'd Means within a row having no common superscript are significantly different (P<.05).


172
research assistant to his coadvisors while conducting
dissertation research.
Thomas is a member of the Poultry Science Association,
World's Poultry Science Association, Gamma Sigma Delta and
Phi Kappa Phi. He was the recipient of the Ruby V. Voitle
Award for Outstanding Graduate Student in 1987-88 and the
Maurice Stein Fellowship for Academic Achievement in Poultry
Economics in 1988. Tom was selected in 1988 as the graduate
student representative on the search committee for a Vice
President of Agricultural Affairs at the University of
Florida. Tom was the recipient of a Certificate of
Excellence in recognition of his presentation of a research
paper at the national Poultry Science Association meetings
in July, 1989.
Thomas married the former Maisha Verwilghen in
Kinshasa, Zaire, in 1980. They presently have two sons,
Jonathan and Benjamin, who are eight and six years old,
respectively.
His main area of interest is in technology assessment
from a bio-economic perspective and his career goal is to be
a member of a multidisciplinary research team that is
responsible for the coordination of financial, logistic,
research and diffusion strategies for a poultry enterprise
or institution.


CHAPTER III
TOWARDS AN APPROPRIATE STRATEGY FOR WEIGHING
BROILERS, BROILER BREEDER PULLETS AND
BREEDER HENS ON-FARM
Introduction
The ability to estimate average body weight and flock
uniformity accurately is an important part of breeder and
broiler managers/ duties. Average body weight estimates of
commercial flocks are used constantly to evaluate breeder
growth and development relative to a particular strain's
standard. Decisions concerning the proper feed allocation
required to consistently achieve a target body weight
objective over a period of time are based on these estimates
and any error in their accuracy will be reflected in the
inefficient growth and production of the flock. Also,
decreases in flock uniformity, i.e., increased variation in
body weight, is a sign of suboptimum husbandry conditions,
the cause of which must be identified and corrected in a
timely manner or production inefficiencies will persist or
worsen.
An appropriate weighing program is an important process
that assures the maintenance of technical and economic
efficiencies in the pullet and breeder houses as well as the
41


61
TABLE 3-6. Effect of sample location (FDD vs. END) on mean
breeder hen and pullet body weight gain (Exp. 3)
Trial
1
Trial 2
Sample
Age
interval
FDD
END
FDD
' END
type
(Age
, wk
; Time)
(g)
(g)
(g)
(g)
Breeder
hen
PND
(36;
AM)
to
(38;
AM)
66
-141
141
16
FXD
(36;
AM)
to
(38;
AM)
77
-159
142
-16
PND
(36;
AM)
to
(38;
PM)
58
-105


FXD
(36;
AM)
to
(38;
PM)
42
-99


PND
(38;
AM)
to
(38;
PM)
-8
36


FXD
(38;
AM)
to
(38;
PM)
-35
60


Pullet
PND
( 8;
AM)
to
(10;
AM)
135
186
167
160
FXD
( 8;
AM)
to
(10;
AM)
141
188
167
143
PND
( 8;
AM)
to
(10;
PM)
92
127


FXD
( 8;
AM)
to
(10;
PM)
84
122


PND
(10;
AM)
to
(10;
PM)
-43
-59


FXD
(10;
AM)
to
(10;
PM)
-56
-67


1 Age interval= 36 wk of age AM weighing to 38 wk of age AM
or PM weighing.
FDD= Feed dump location
END= End location
PND= All birds penned
FXD= Fixed quantity
SD= Standard deviation
Sig= Significance (P<.05)


1?
transfers the value of a momentary load of a bird standing
on it into a computer!2ed weight indicator. The hardware
contains a set of adaptive, time-varying filters used to
detect exact weights of a moving, live load. Also, it can
differentiate between, and adjust for, weights caused by
debris left on the platform by establishing previously
defined tolerance limits. The tolerance definitions are
based on the known standard deviations of a normal flock
plus a margin of safety. Each weighing is recorded either
as an in- or out-of-range weight and is placed in its proper
distribution. Pooled in-range weights are subjected to
statistical processing for average and standard deviation
calculations. The calculations are recursive, so that
average and standard deviations are up-dated on each
weighing and all output, including a distribution table and
histogram, are printed on demand.
The reliability of an automatic weighing system is
limited by accuracy of readings and numbers of birds using
the scale. Turner et al. (1983) found there was good
agreement between automatic and manual weighings when a
perch-type platform was used. Their results showed no bias
by the frequent use of the perch by certain individuals to
the exclusion of others. There was, however, an indication
that broilers used the perch less frequently with increasing
age. Newberry et al. (1985) conducted a study with roasters
kept to 10 wk of age to evaluate this effect. Mean body


144
PRICE SITUATIONS
FIGURE 6-3, Sensitivity of pullet average total cost to
changes in component costs at 20, 25, and 30 weeks of age for
the STD feeding program (CHK=chick, PFD=pullet feed,
PPAY=grower pay, PMRT=pullet mortality, DENSITY=pullet housing
density).


76
Hen-day production of double-yolked eggs as affected by
feed treatment is illustrated in Figure 4-5, Proportional
increases in feed restriction resulted in proportional
decreases in hen-day production of double-yolked eggs. The
-24% treatment had significantly lower production of double-
yolked eggs than STD (Table 4-4). Katanbaf et al.. (1989b)
showed that a standard feed restriction program will produce
fewer double-yolked eggs than an ad libitum feeding programs
by a difference of 3,5 to 4.0 times. The incidence of
double-yolked eggs has been shown to be both strain and
season related (Christmas and Harms, 1982).
Hatching eggs per hen housed did not differ
significantly among feeding programs (Table 4-4). The data
presented in Table 4-5 compares production cycles by
chronological and physiological age. Data based on
physiological age was determined by adjusting the first day
at 5% production for each replicate to be the start of the
production cycle. This adjustment permitted a direct
comparison of the production cycles by discounting treatment
effects for the delay in sexual maturity (time). Comparison
of the -24% and STD production response to feed treatment,
adjusted for time, revealed no differences between these
treatments.
Egg Characteristics
The effect of the STD and -24% feed treatments on mean
egg weight and specific gravity during the production period


44
with the same procedure repeated the following day. Crated
birds were weighed on an electronic scale (Detecto, model
EF-218-56) with a gross capacity of 90.7 kg (200 lb) and a
precision of 45 g (0.1 lb). The four crate weights for each
trial were pooled and the average body weight and change
(gain or loss) for each time period calculated.
Experiment 2
Trials 1. 2 and 3. Three weight class groupings,
totaling 274 Arbor Acres broiler breeder females, 41 wk old
and near peak production, were used to test the accuracy of
different types of scales (electronic vs. mechanical) and
sample units (individual vs. group) in determining average
body weight and uniformity. Three groupings (trials) were
used to simulate body weight conditions found on different
farms. Each trial consisted of six pens containing ca. 15
adult breeder hens. Birds were crated seven or eight birds
to a crate depending upon the population size within a pen.
The weigh routine was as follows: crate weights (GRP)
were measured on an electronic Detecto scale to the nearest
45 g; birds were individually (IND) removed from the crate
and weighed, first on an electronic (ELC) scale (Weltech,
model BW-1) to the nearest 1.0 g and then on a mechanical
(SPR) spring scale (Salter, model 235) to the nearest 45 g.
All weighings were conducted by the same person and data
recorded by a technician to expedite the flow of procedures.


BIO-ECONOMIC ANALYSIS OF SELECTED
BROILER BREEDER MANAGEMENT PRACTICES
BY
THOMAS RICHARD FATTORI
A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
1989


158
(higher average cost) was capitalized at the start of the
breeder hen laying period, relative to standard. After 40
wk of production the average cost per breeder hen was still
higher for the most restricted feeding program. However,
when average total cost is expressed on the basis of a dozen
hatching eggs produced there was essentially no difference
between these feeding programs.
Projected average total cost (based on extrapolated
data) for the standard and most restricted feeding programs
beyond 65 wk of age suggests that the restricted birds would
have a lower average total cost than standard. This implies
that by extending the laying period beyond ca. 67 weeks of
age there will be an economic advantage for the severely
restricted birds.
Furthermore, severe feed restriction as a management
technique has the potential of significantly lowering the
average total cost of a dozen hatching eggs if pullet
housing density can be adjusted so that an equivalent bio
mass is maintained without any detrimental biological
affects to growth and production.
In conclusion, this dissertation demonstrated that a
breeder manager can increase returns to pullet growers,
hatching egg producers and the broiler integrator by: 1)
developing a body weight monitoring and control program that
assures the transmittal of accurate and timely information
from on-farm to the appropriate decision maker; 2) using


51
difference in uniformity (Table 3-5). However, the END
location was greater at 36 wk while the FDD was greater at
38 wk. Furthermore, the 38 wk, PM weighing failed to detect
differences in location suggesting that the END location
actually gained weight during the day by feeding and
drinking later. Perry et al. (1971) noted that after
laying, a period of feeding and drinking followed, which
suggests earlier laying by the END location. Trial 2 does
not substantiate these findings. No significant differences
in average body weight or uniformity between locations were
detected for any PND sample. It is difficult to determine
from these data if the differences found in Trial 1 at the
various ages were due to changing flock dynamics or sampling
error. Consistency in the uniformity data as well as the
low number of detected outliers suggests that there could be
significant behavioral differences at various locations in
the house. Appleby et al. (1984) found considerable
movement of both males and females throughout the house.
However, their study was conducted in buildings 46 m long,
whereas these data were collected in buildings 122 m in
length.
Time of weighing. The importance of consistently
weighing at the same time each scheduled weighing
(Experiment 1) is underscored with breeder pullets and
laying breeder hens. Two principal observations can be made
from the data presented on both AM and PM weighings in


CHAPTER VII
SUMMARY AND CONCLUSIONS
In keeping with FSR/E methodology, this chapter is
written for the broiler breeder manager (client). It
presents an overview of the research findings presented in
this dissertation and makes practical recommendations in
broad terms so that breeder managers can understand, adjust
and utilize them within the context of their own particular
set of conditions.
A successful broiler breeder management program is one
that optimizes the use of feed, labor, capital and other
resources in the production of placeable chicks. To be
successful the breeder manager is required to make effective
decisions concerning the use of these resources during both
the rearing and production periods. This dissertation
examined four areas of breeder management that are important
to this decision making process. Specifically, the breeder
manager needs to: l) establish an effective body weight
monitoring and control program? 2) maximize the number of
placeable chicks per hen housed from a laying program? 3)
target the onset of sexual maturity; and 4) optimize returns
from pullet rearing and breeder hen laying programs.
150


6-7 Sensitivity of breeder hen average total cost
to changes in feed costs (BFD) or costs due to
breeder hen mortality (BMRT) at 40 weeks of
production and for the STD or -24% feeding
programs 147
6-8 Sensitivity of breeder hen average total cost
to changes in pullet depreciation costs (PUL$) or
costs due to breeder hen mortality (BMRT) at 40
weeks of production for the STD and -24%
feeding programs 148
6-9 Effect of changes in pullet housing density on
average total cost per pullet (ATC/P) at 5%
production 149
6-10 Effect of adjusted pullet housing density on
average total cost of a dozen hatching eggs
(ATC/E) on a STD and -24% feeding program, with
age 149
xi


TABLE 5-1. Correlation coefficient (r) and the significance probability that the correlation
AGE
Trait
BWT
FTPD
LIPID
OVARY
OVID
(wk)
r
Prob.
r
Prob.
r
Prob.
r
Prob.
r
Prob.
20\22
BWT
.86
*
.71
*
.63
*
.48
.03
FTPD
.93
*
.44
.05
.32
.17
.40
.08
LIPID
.55
.01
.53
,02
.57
.01
.34
.14
OVARY
.64
*
.51
.02
.57
.01
.55
.01
OVID
.79
*
.82
*
.47
.04
.64
*
BURSA
.60
.01
.64
*
.18
.44
.34
.14
.57
.01
SHANK
.71
*
.53
.02
.46
.04
.54
.02
.46
.04
ARCH
.83
*
.80
*
.55
.01
, 66
*
.71
*
COMB
.73
*
.61
*
.19
.43
.40
.08
.55
.01
HEAD
.68
*
.66
*
.29
.21
.34
.14
.56
.01
24\26
BWT
.90
*
.66
*
.17
.48
.51
.02
FTPD
.92
*
.75
*
.29
.22
.55
.01
LIPID
.43
.06
.56
.01
.07
.78
.27
.25
OVARY
.24
.30
.23
.32
.62
*
.79
*
OVID
.32
.16
.38
.10
.73
*
.89
*
BURSA
.15
.53
.07
.76
.12
.62
-.15
.52
-.11
.64
SHANK
.62
*
.49
.03
-.12
.63
-.25
.28
-.16
.49
ARCH
.76
*
.81
*
.60
.01
.38
.10
.56
.01
COMB
.77
*
.72
*
.47
.04
.39
.09
.58
.01
HEAD
.64
*
.60
.01
.23
.34
.15
.52
.39
.09
28\ALL
BWT
.88
*
.54
*
.34
*
.58
*
FTPD
.79
*
.55
*
.35
*
.54
*
LIPID
.70
*
.61
*
.45
*
.67
*
OVARY
.33
.16
.29
.21
.30
.20
.83
*
OVID
.68
*
.47
.04
.57
.01
.80
*
BURSA
-.14
.56
-.15
.52
-.03
.89
-.47
.04
-.33
.16
SHANK
.63
*
.34
.15
.51
.02
-.13
.58
.20
.39
ARCH
.74
*
.60
.01
.59
.01
.54
.01
.75
*
COMB
.64
*
.57
.01
.39
.09
.35
.13
.42
.07
lmw: tr
HEAD
.69
TDn -P~*- ,
*
t tottah
.46
.04
.42
rvEJATVvr
.07
.36
.12
.55
.01
SHANK*shank length, ARCR=pubic spread, COMB=comb factor, HEAD=head score.
220, 24, and28 wk of age below the diagonal and 22, 26, and ALL (pooled) wk of age above the diagonal.
^Significance probability <.01.
101


133
O, -.092, -.193 and -.300 dollars for the +8%, STD, -8%,
-16% and -24% feeding programs, respectively. This
increase in pullet DNSTY decreased the ATC/P at 5%
production for STD feeding program from $6.005 to $5.705 and
resulted in a decreased ATC/P of $.129 lower than STD.
Potential savings from increased pullet DNSTY is passed
directly to the breeder laying accounting period. Pullet
rearing costs (PUL$) represent ca. 42% of the average total
cost of producing a dozen hatching eggs. A comparison of
the effect of reducing PUL$ by $.30 on ATC/E for the STD and
-24% programs is illustrated in Figure 6-10. The lower PUL$
cost resulting from higher pullet DNSTY shifted the ATC/E
curve for the -24% program to the left. The magnitude of
this displacement was equivalent to ca. $.02 /DZHE.
Furthermore, the ATC/E for the two feeding programs reached
an equivalent value at ca. 62 wk of age, which was 5 wk
earlier than base housing density conditions (67 wk).
In summary, each wk of delayed sexual maturity from
severe feed restriction increased the ATC/P at 5% production
by ca. 1%. Decreased feed costs offset other pullet
variable costs at a common chronological age, but not when
evaluated to the physiological age of 5% production.
Increased pullet rearing costs, relative to standard, were
carried over into the breeder hen accounting period and
comprise ca. 40% of the ATC/B when evaluated through 40 wk
of production. When ATC were determined relative to


67
al., 1989b), increase livability (Lee et al.. 1971; Wilson
and Harms, 1986, Katanbaf et al.. 1989a), increase fertility
and hatchability (McDaniel et al.f 1981b; Bilgili and
Renden, 1985), and improves egg production (Leeson and
Summers, 1982; McDaniel, 1983; Wilson and Harms, 1986;
Hocking et al.. 1987; Katanbaf et al.. 1989b). These
effects will also be influenced by photoperiod, temperature
and other environmental factors that can alter the
reproduction process.
The primary breeder companies currently recommend
various degrees of feed restriction for their particular
strain which permit a relatively narrow range of growth
curves to be followed in different environments. The
optimality of these prescribed standards are of issue and
raise interest in feed allocations below current
recommendations (severe restriction).
If the overall objective of the breeder manager is to
maximize the number of placeable chicks per hen housed over
a normal production period, then the optimal growth curve
and corresponding feeding program for a particular strain
must be identified. The growing consensus is that current
recommendations lead to an overweight breeder flock that
does not meet this objective.
Therefore, the overall objective of this experiment was
to evaluate the breeder's recommended growth curve by
determining the relationship between various degrees of


18
weights obtained on the automatic weighing system were
significantly lower at 7 and 10 wk of age than those
obtained manually. They attributed this result to the
larger birds at later ages perching with part of their
weight in contact with the floor and recommended raising the
perch higher with age. Birds observed on the weighing perch
on one day of the week were 3.5 times more likely to use the
perch again on the following two days. Perching rate
decreased from 41.6 birds/h in wk 1 to 4.3 birds/h in wk 10.
Blockhuis et al. (1988) reported that in broiler trials
comparing manual to automatic weighing systems, the
automatic (platform scale) gave a consistently lower value
than weighing by hand. The difference becoming greater as
the birds aged from 4 to 6 wk. A study on the behavioral
response to the electronic scales made with both male and
female broilers, showed that the percentage of the tagged
birds that made use of the scales and the average frequency
of use of the scale differed significantly with age and sex.
The average frequency of use of the scale was higher for
females especially at 6 wk of age. This would explain the
lower average weights generated by the automatic weighing
system. A possible explanation for this behavior would be
the relatively lower activity of the heavier males. Between
flocks there was considerable variability in the behavior of
the flocks towards the weighing system. Those flocks that
demonstrated higher male activity had average weights from


26
the laying hens. Therefore, any feeding program designed to
promote early egg production also enhances early average
body weights, without necessarily affecting the actual
weights of the laying hens. These researchers found that
earlier maturity and higher egg production were associated
with higher energy intake during the prelay period. The
effect of increased energy during this period on egg weight
was dependent on the age at which the increase in energy was
provided.
McDaniel (1983) showed that quantitative differences in
feed allocation during the prelay period significantly
affected shell quality and egg weight throughout production.
Increased feed allocation, i.e., 176 g/bird/d, from 17
through 20 wk of age stimulated an earlier onset of
production when compared to a more gradual increase in feed
allocation.
Protein
Research conducted by Cave (1984b) showed that protein
levels (15.4 vs. 18.1%) during the prelay period had no
effect on age at 50% production, egg weight, incidence of
cracked eggs, hatchability or mortality. However, the 18.1%
protein treatment showed higher levels of egg production
through 50 wk of age. One possible explanation of this
finding relates to the important changes in the development
of the reproductive system at this time (Yu and Marquardt,
1974). Cave (1984b) suggested that perhaps the higher


131
After this age ATC/E for STD turned upward as continued
expenses (BFD and BMRT) overtook reduced production.
Whereas, ATC/E for the -24% program continued to fall
through 78 wk of age.
The effect of feeding program on ATC/E before salvage
adjustments were made is presented in Table 6-7 on a
chronological age basis. As the breeder hen aged, ATC/E
dropped at a curvilinear rate with the more restricted
feeding programs falling from a higher ATC/E value at 50 wk
of age. These differences among feeding programs represent
the ATC/E for delayed sexual maturity, which were
progressively overcome as the hen aged. Derived ATC/E for
70 and 75 wk of age suggest that the -24% program became
more economical (lower ATC/E) than STD by 70 wk. Figure 6-6
implies that under the assumptions made in this analysis the
-24% program achieved an equal ATC/E with the STD program at
ca. 67 wk of age (data projected for one week) and resulted
in a lower ATC/E than STD when production was projected
beyond this age.
Sensitivity analysis conducted on ATC/E data from STD
and -24% feeding programs revealed that after 40 wk of
production ATC/E was most sensitive to changes in BFD, PUL$,
BPAY and BMRT, in that order. A 20% change in component
BFD, PUL$, BPAY and BMRT costs on a STD feeding program
resulted in ATC/E to be changed by + .124, .088, .06 and
.016 dollars, respectively. Similarly, the -24% program


123
Contract payment costs
Pullet contract costs. Pullet-grower payment cost
(PPAY) was predicated on contractual arrangements. The
assumption was made that a pullet-grower would be paid at
the base rate of $.0275 per .0929 m 2 / wk for each flock
and that chicks would be housed at the base bird density of
.1626 m2 (1.75 ft2) per bird. From these standards,
cumulative pullet grower payments increased at the rate of
$.04812 /pullet/wk to a particular age.
Breeder hen contract costs. Cumulative hatching egg
data were obtained from each experimental treatment by
subtracting the double-yolked eggs from hen-day production
of total eggs and averaged into a weekly value. This
procedure was used due to a significant feeding program
effect on the incidence of double-yolked eggs (Chapter IV,
Table 4-4). Average weekly production of adjusted total
eggs was then further adjusted for commercial eggs, e.g.,
undersized, dirty, or cracked eggs, at an equivalent rate
(.0005%/wk) for all feeding programs, which allowed the
removal of 2% commercial eggs after 40 wk of production.
Cumulative production of hatching eggs was then adjusted for
breeder hen mortality and expressed as dozens of hatching
eggs per breeder hen survivor. This value for each feeding
program represents the output function in the production
process.


135
TABLE 6-1. Base costs, production coefficients and 20%
adjustments used in sensitivity analysis of a pullet rearing
enterprise
Price
Situations
-20%
BASE
+20%
CHK cost1, $/pullet
1.622
2.026
2.432
Mortality
Pullet, %/wk
Cockerel, %/wk
.16
.41
.20
.50
.24
.60
Rearing feed, $/kg
* 108
.135
.162
Service &
Supervision, $/Surv.
.0104
.013
.0156
Pullet density,
m2/ pul let
Ft2/pullet
.1301
(1.40)
.1626
(1.75)
.1951
(2.1)
Grower rate,
$/m2/wk
$/Ft2/wk
.2368
(.0220)
.2960
(.0275)
.3552
(.0330)
XCHK cost= combined pullet ($1.70) and cockerel cost ($2.90)
at a 9:1 female to male ratio.


24
alternative to this system for breeders is the use of cages,
which necessitates the labor-intensive practice of
artificial insemination. If breeder females are to be kept
in cages, appropriate feeding and body weight control
programs need to be developed. McDaniel (1974) showed that
broiler breeder hens generally produce more eggs when kept
in cages. However, Fuquay and Renden (1980) reported that
hens maintained in floor pens produced more eggs per day
than hens kept in cages. In their experiment caged females
had significantly higher body weights and significantly
greater variation (less uniformity) in body weights than
floor-reared females. Caged birds generally exhibited
equivalent fertility and hatchability through 59 wk of age,
although they also had higher levels of mortality than floor
birds.
Petitte et al. (1982) reported that caged breeder hens
had significantly heavier body weight and egg weight as
compared to floor birds. Neither mortality nor cumulative
production showed any difference between housing method?
however, during the peak production period the caged hens
exhibited significantly higher levels of production.
A follow-up study by Petitte et al. (1983) showed that
the fertility of the artificially inseminated caged breeders
was significantly lower than that of the naturally mated
birds. Hatchability of eggs at 26 wk was not affected by
housing method? however, hatchability of eggs set at 36 and


SHANK
107
o= + 8 7. 0= SID # = -8% v= -16% 0= -24?:
FIGURE 5-1. Effect of feed treatment on shank length (mm)
with respect to age (wk) and body weight (g)


16
llegronle Weighing,Systems
Efficient poultry production requires accurate
information and statistics that enable decision makers to
act in a timely manner. This is especially true for
monitoring and controlling growth and development of almost
every class of poultry. An ideal weighing program would
supply accurate day to day information on growth and
uniformity at a reasonable cost. A variety of electronic
microprocessor-based scales are currently available for
almost every poultry production system and offer the
potential to fulfill these needs.
Lott et al. {1982} and Stutz et al. (1984) described
the development and application of an automated weighing and
analysis system for growth and efficiency studies. They
noted that the prime advantages of such a system were in the
reduction of transcription errors and labor requirements
compared to conventional methods. Feighner et al. (1986)
reported that the implementation of a computerized weighing
system resulted in a 60 to 65% savings in time over manual
acquisition and use of a calculator to analyze the data.
The portability of the micro-computer made it possible to
transport to remote research and production areas.
Meltzer and Landsberg (1988) described the process of
recursive (continual up-dating) calculations and flexibility
of modern data loggers in collecting and analyzing body
weight data. Briefly, a weighing sensor (load cell)


141
TABLE 6-7. Average total cost of a dozen hatching eggs
produced to a common age by feeding program, calculated at
base prices and before salvage adjustment
Feeding Program
+8%
STD
-8%
-16%
-24%
Average Total
dozen hatching
Cost/
eggs
50 wk
1.395
1.371
1.386
1.508
1.508
55 wk
1.297
1.280
1.276
1.350
1.354
60 wk
1.233
1.216
1.206
1.257
1.253
65 wk
1.197
1.181
1.165
1.205
1.192
Proiected
70 wk
1.186
1.171
1.150
1.181
1.158
75 wk
1.185
1.172
1.148
1.171
1.138


9
Relevance to Farming Systems Research and Extension
The strength of the Fanning Systems Research and
Extension (FSR/E) approach to technology generation is
derived, in part, from its systems perspective while
accounting for the biological as well as the socio-economic
factors that impact on the production process. The
vertically integrated broiler production systems of today
are highly complex by agricultural standards and economies
of scale are required in their competitive marketplace. In
such a system, savings of a hundredth of a cent per pound of
product from increased technical efficiencies can translate
into millions of dollars of added net income for growers,
breeders and integrator.
Therefore, FSR/E methodology is perhaps the most
appropriate approach to technology generation at the breeder
level in that it prescribes a complete socio-economic, as
well as biological, analysis of the production system. The
methodology utilized in this research drew upon
multidisciplinary issues that ranged from information
systems to the physiological aspects of sexual maturity. The
result is a dissertation that is more comprehensive than
would have been attained if "traditional" procedures were
followed. Furthermore, client participation in problem
identification and diagnoses was sought out, and diffusion
of research findings back to the client was achieved in a
workshop setting.


ARCH
109
28
o= +8* 0 = STD eg, = 8 % <3? = -16% £= -2 4%
FIGURE 5-3. Effect of feed treatment on pubic spread or arch
(cm) with respect to age (wk) and body weight (g).


TABLE 3-2. Effect of scale type (ELC vs. SPR) and sample
unit (IND vs.GRP), on mean adult breeder hen and breeder
pullet body weight and uniformity (SD), (Exp. 2)
57
Age Trial Scale type Sample unit
(wk)
No
#
ELC
SPR
Sig.
IND
GRP
Sig.
38
1
N no.
90
90
90
12
mean, g
4029
4063
NS1
4029
4074
NS
SD, g
399
399
NS2
399
196
*
38
2
N no.
90
90
90
12
mean, g
3781
3811
NS
3881
3874
NS
SD, g
336
331
NS
336
152
*
38
3
N no.
94
94
94
12
mean, g
3597
3624
NS
3597
3644
NS
SD, g
319
322
NS
319
125
*
40
1
N no.
90
90
90
12
mean, g
4036
4063
NS
4036
4053
NS
SD, g
415
419
NS
415
191
*
40
2
N no.
89
89
90
12
mean, g
3816
3842
NS
3816
3797
NS
SD, g
361
360
NS
361
237
*
40
3
N no.
94
94
94
12
mean, g
3635
3663
NS
3635
3632
NS
SD, g
320
325
NS
320
289
*
8
4
N no.
111
111
mean, g
844
855
NS


SD, g
130
133
NS

8
5
N no.
107
107
mean, g
862
847
NS


SD, g
101
97
NS
1 t-test on sample means (P<.05).
2 F-test ratio on sample variance (P<.05).
ELC= Electronic scale SD= Standard deviation
SPR= Spring scale Sig= Significance (P<.05)
IND= Individually weighed
GRP= Group weighed


8
3.characterize in graphic form the age and body-
weight relationships to changes in the various physical
attributes;
and 4. relate findings from the characterization process
to possible field applications.
Regarding Hypothesis 4
The experimental objectives regarding hypothesis 4 were
to: 1. examine the effect of severe feed restriction on
pullet rearing cost structure;
2. determine the cost of delayed sexual maturity due
to various levels of severe feed restriction;
3. test the sensitivity of the average total cost of
rearing a pullet to 5% production to changes in component
costs;
4. examine the effect of severe feed restriction on
breeder hen cost structure;
5. compare breeder hen average total costs on a
survivor and per dozen hatching eggs basis;
6. test the sensitivity of average total cost of
breeder hen hatching egg production to changes in component
costs;
7. estimate the changes in pullet rearing cost
structure due to changes in pullet housing density;
and 8. estimate the changes in breeder hen laying cost
structure to changes in pullet housing density.


28
gravity were significantly affected by hen age and not feed
treatment.
Lighting Programs
An important management tool that must be considered
along with a planned feeding program is an appropriate
lighting program. A well managed lighting program is a cost
effective way to regulate the onset of sexual maturity. The
objective being the synchronization of sexual maturity,
through feeding and lighting programs, with management
production and scheduling needs. The normal procedure is to
increase the length of the daily photoperiod from an
inhibitory 6 to 12 h/d to a stimulatory photoperiod of 12 to
17 h/d, starting at point-of-lay (Morris, 1967).
Recommendations for light stimulation of breeder
pullets should be strain specific according to Cave (1984a).
He found significant differences in the production response
to abrupt vs. gradual increases in light stimulation for two
different strains of meat-type birds. This finding was
contrary to conclusions drawn by Proudfoot et al (1980) who
reported no important genotype X photoperiod treatment
interaction when evaluating various abrupt and gradual
lighting programs. However, Proudfoot et al. (1984)
concluded that dwarf genotypes also require a different
light management program than normal strains for optimum
reproductive performance.


88
RESEARCH PERIOD
FIGURE 4-1. Average weekly high (HI) and low (LO)
temperatures and hours of daylight (LIGHT) during the
research period.
FIGURE 4-2. Live body weight from hatching to 62 weeks of
age as affected by feed treatment.


163
Gomez, K. A., and A. A. Gomez, 1984. Statistical Procedures
for Agricultural Research. John Wiley and Sons, Inc.,
New York, NY.
Gvaryahu, G., D. L. Cunningham, and A. Van Tienhoven, 1989.
Filial imprinting, environmental enrichment, and music
application effects on behavior and performance of meat
strain chicks. Poultry Sci. 68:211-217.
Gvaryahu, G., N. Snapir, and B. Robinzon, 1987. Research
note: Application of the filial imprinting phenomenon
to broiler chicks at a commercial farm. Poultry Sci.
66:1564-1566.
Harms, R. H., 1984. The influence of feeding program on
peak production and avoiding sudden declines in
production with broiler breeders. Poultry Sci.
63:1667-1668.
Harms, R. H., S. M. Bootwalla, and H. R. Wilson, 1984a.
Performance of broiler breeder hens on wire and litter
floors. Poultry Sci. 63:1003-1007.
Harms, R. H., F. B. Mather, C. R. Douglas, and S. M. Free,
1984b. A method for weighing pullets during the
growing period. Poultry Sci. 63:443-446.
Harms, R. H., R. A. Voitle, and H. R. Wilson, 1979.
Performance of broiler breeder pullets grown on various
grower programs. Nutr. Rept. Int. 20(4):561-566.
Harms, R. H., and H. R. Wilson, 1980. Protein and sulfur
amino acid requirements of broiler breeder hens.
Poultry Sci. 59:470-472.
Hocking, P. M., A. B. Gilbert, M. Walker, and D. Waddington,
1987. Ovarian follicular structure of White Leghorns
fed ad libitum and dwarf and normal broiler breeders
fed ad libitum or restricted to point of lay. Br.
Poult. Sci. 28:493-506.
Hocking, P. M., D. Waddington, M. A. Walker, and A. B.
Gilbert, 1989. Control of the development of the
ovarian follicular hierarchy in broiler breeder pullets
by food restriction during rearing. Br. Poult. Sci.
30:161-174.
Hubbard Farms, Inc., 1988-89. Hubbard breeder pullet
management guide. Walpole, NH.


37
recommendations for protein and sulfur amino acid
requirements (Harms and Wilson, 1980) by suggesting that
nutrient specifications for broiler breeders include daily
intakes of 20.6 g protein, 754 mg sulfur amino acids, 400 mg
methionine, 938 mg lysine, 1379 mg arginine, 256 mg
tryptophan, 4.07 g calcium, 683 mg total phosphorous, and
170 mg sodium. Pearson and Herron (1981) recommended 19.5
g/d crude protein when reared on litter and when amino acid
intake was balanced. Caged breeder hens were shown by
Pearson and Herron (1982b) to require 16.5 g/d protein .
The absolute energy requirement associated with optimum
production will depend upon the actual maintenance energy
requirement which is likely to differ between cage and floor
systems as well as between strains (Pearson and Herron,
1982b).
Double-Yolked Eggs
The phenomenon of multiple ovulations (double-yolked
eggs) in the chicken has been reviewed by Romanoff and
Romanoff (1949). Zelenka et al. (1986) noted there appears
to be two major categories of multiple ovulations,
sequential and simultaneous. Sequential multiple ovulations
result in extra-calcified compressed-sided eggs, whereas,
simultaneous multiple ovulations result in eggs with more
than one yolk. Conrad and Warren (1940) reported three ways
that double-yolked eggs might occur. First, 65% resulted
from the simultaneous development and ovulation of two ova.


149
AGE AT 5* PRODUCT ION., GWK}
FIGURE 6-9. Effect of changes in pullet housing density on
average total cost per pullet (ATC/P) at 5% production.
AGE, CWQ
FIGURE 6-10. Effect of adjusted pullet housing density on
average total cost of a dozen hatching eggs (ATC/E) on a STD
and -24% feeding program with age.


132
resulted in ATC/E to be changed by + .119, .089, .06 and
.016 dollars, respectively. The sensitivity of ATC/E to
changes in BFD and BMRT costs on STD and -24% feeding
programs is illustrated in Figure 6-7 and changes in PUL$
and BMRT in Figure 6-8. Sensitivity of ATC/E to changes in
BFD was affected by feeding program. The slopes of the BFD
lines in Figure 6-7 indicated that ATC/E was more sensitive
to increases in BFD costs on a STD program than when fed a
-24% program. However, under the situation of lowered BFD
costs the difference in feeding program was not as apparent.
Generally, the effect of feed restriction below current
recommendations on ATC/E through 40 wlc of production was a
slight shifting to lower values.
Pullet Housing Density
Justification for increasing the density of pullets in
a rearing house can be made for the more restricted feeding
programs on the basis of maintaining an equivalent bio-mass
(total live-bird weight) in a house. The average live
weight of pullets for a range of ages commonly used for
transferring pullets to a breeder house are listed in Table
6-8. The relative difference in these body weights indicate
that changing the pullet housing density by -7, 0, +7, +14
and +21% will result in ca. an equivalent bio-mass for each
feeding program at any probable transfer age.
The effect of changing pullet housing density on ATC/P
is illustrated in Figure 6-9. where ATC/P changed by +.085,


154
lower for the -16% and -24% feed treatments. However, there
were corresponding and significant decreases in hen-day
production of double-yolked eggs among feed treatments. The
more restricted birds produced fewer double-yolked eggs and
thus increased their relative percentage of settable eggs.
When production was adjusted for double-yolked eggs and
mortality (hen-housed basis) there were no significant
differences between the standard and -24% feed treatments at
64 wk of age.
No differences were found in egg weights pooled over
the laying period due to feed treatment. Average egg weight
at the beginning of the production period was generally
higher for the more restricted birds which again contributed
to the difference in the number of settable eggs among feed
treatments. The more restricted birds produced eggs with
significantly better egg shell quality, as measured by
specific gravity, over the laying period. This difference
in shell quality was due to differences in egg weight,
although the -24% feed treatment had better shell quality
and equal egg weight relative to standard when averaged over
the laying period. In this study there were no differences
in fertility or hatchability of all eggs set due to feed
treatment.
Proportional differences in quantity of feed, protein
and energy consumption were a result of the feed allocation


TABLE
with
5-4. Effect of feed treatment (mean + SEM)
sexual maturity
on
various
physical
attributes associated
Age
Feed
BWT1
SHANK
ARCH
COMB1
HEAD1
(wk)
treat.
(g)
(mm)
(cm)
(cm' )
(no.)
18
+8X
2069
+
70
112.8 + 1.0a
2.44
+ ,10a
.21
+
,02a
1.6
+ ,2a
STD
1848
+
58
110.4 + 7ab
2.33
+ ,09a
.21
+
.01a
1.4
+ ,lab
-8X
1768
+
57b
108.1 + .9b
2.33
+ ,07a
.19
+
02a
1.4
+ ,1a15
-16X
1741
+
57b
108.1 + l.lb
2.32
+ 09.a
.22
+
02a
1.4
+ .l833
-24X
1514
+
55c
105.1 + .9
2.05
+ 06b
.14
+
,01b
1.1
-lb
20 +8X
STD
-8X
-16X
-24 X
2346 + 75a
113.5 +
1.0a,
2.70 +
05a
.29 +
,02a
2.0 +
2171 + 61a
112.2 +
gb
2.53 +
,05a
.26 +
.08
1.5 +
1856 + 56b
110.1 +
. 9b
2.27 +
. 06b
.20 +
.01
1.3 +
1677 + 55c
107.6 +
1.0d
2.14 +
.05"
.22 +
. 06bc
1.4 +
1625 + 60c
107.1 +
1.0d
2.19 +
. 09b
.18 +
.02
1.3 +
+8X
2486
+
74a
58ab
113.8
+
6;
STD
2336
+
112.3
+
81
-8X
2184
i
55b
112.4
+
1.2
-16X
2259
+
47d
111.3
+
. 9
-24X
1724
+
51d
107.9
T
.8'
2.78 +
,08a
.50 +
.06a15
2.8 +
.2'
2.70 +
06a
.56 +
07a
3.0 +
.2'
2.61 +
,05a
.39 +
04bc
2.2 +
.2
2.39 +
. 09b
.35 +
04d
1.9 +
.21
2.17 +
.09
.23 +
. 02d
1.4 +
.1'
+8X
2855 + 21a
115.0 +
,9a
3.31 +
,12a
.90 +
06a
3.3 +
STD
2782 + 61a
115.2 +
9
2.92 +
. 12b
.69 +
.07b
2.7 +
-8X
2353 + 64"
110.5 +
. 8b
2.67 +
. 08bc
.56 +
,08b
2.3 +
-16X
2259 + 47b
111.3 +
1.0"
2.58 +
.09
.48 +
,06d
2.5 +
-24X
2008 + 38
108.9 +
1.0b
2.31 +
. 05d
.35 +
.05d
1.8 +
+8X
3075 + 88a
115.3 +
.3a.
4.00 +
16a
1.06 +
,10a
3.2 +
.2b
STD
2806 + 88"
113.9 +
1.0
3.42 +
12k
1.11 +
,09a
3.8 +
,2a
-8X
2767 + 70b
115.7 +
8a
3.38 +
. 15b
.94 +
10ab
2.9 +
,lb
-16X
2382 + 76
111.3 +
1 0bc
3.28 +
. 14b
.70 +
. 07b
2.7 +
2b
-24X
2215 + 66
109.6 +
1.2
2.75 +
.12
.50 +
.07
2.3 +
.2
28 +8X
3146 + 54a
115.0 +
7a.
5.16
+
,09a
1.88 +
. i5a
4.7 + ,1a
STD
2924 + 81"
113.7 +
gBb
4.56
+
,10b
1.37 +
. 13b
4.1+ .2ab
-8X
2900 + 71b
114.7 +
gBb
4.11
+
. 17^
1.08 +
. 08b
3.6 + 2b
-16X
2612 + 48
112.5 +
1 0b
3.97
+
. 21d
1.13 +
. 17b
3.9 + 2b
-24X
2391 + 82d
110.9 +
1.1
3.58
+
. 27d
.60 +
.07
2.9 + .3
1BWT=Body weight;
COMB=height
X width;
HEAD=
=visual
score,
1 (least
developed)
to 5 (most
developed).
*dMeans within a column and having no common superscript are significantly different (P<.05) .
106


29
Payne (1975) reported that an abrupt increase in
photoperiod from 6 to 16 h/d had a significant effect in
advancing the onset of sexual maturity when compared to a
gradual 1 h/wk increase from 6 to 16 h/d. However, this
procedure produced more smaller eggs than the gradual
increase in photoperiod. He also found that pullets reared
on a 6 h photoperiod then gradually increased to 16 h by 34
wk of age had improved reproductive performance and weighed
significantly less, both at the beginning and end of the
laying period when compared with pullets reared using a
constant 15 h photoperiod.
Whitehead et al. (1987) also compared abrupt vs.
gradual lighting programs. The gradual program started at
18 wk of age and increased .5 h/wk to a maximum 18 h at 38
wk of age. The abrupt program began at 19 wk with a rapid
increase of l h/wk to 26 wk then a gradual .5 h/wk increase
to a maximum 17 h at 30 wk of age. The different lighting
programs had no significant effect on any aspect of
reproduction performance in dwarf broiler breeders.
Ingram et al. (1988) demonstrated that initiation of a
stimulatory lighting program at 20 wk was superior to one
initiated at 16 wk of age. Light treatments were ca.
13L:11D increased by 15 or 30 minutes to 15L:9D at 24 wk.
In this experiment, lighting program had a greater effect on
the more restricted (lighter body weight) group.


CHAPTER VI
ECONOMIC ANALYSIS OF SEVERE FEED RESTRICTION
ON BROILER BREEDER PULLET REARING AND
BREEDER HEN HATCHING EGG PRODUCTION
Introduction
Growth and reproductive performance of broiler breeder
parent flocks have a direct and important impact on net
returns to a broiler integrator. Strain and Nordskog (1962)
regarded the breeding hen as the basic profit unit in the
integrated broiler industry. However, today, the breeder
parent has an indirect effect (transfer of genetic potential
to its progeny) on net returns that is more important than
the direct effect. The genetic capacity of the breeder
progeny to convert feed efficiently and yield more meat is
of primary economic importance to the broiler integrator.
Still, economic gains from increased broiler breeder
reproductive efficiency can be significant given the scale
of the broiler industry today.
Previous research on the biological effects of feed
restriction on female broiler breeder growth and
reproduction has indicated a number of technical advantages
to such feeding programs. Unfortunately, the economic
117


146
AGE AT 5* PRODUCTION, CWQ
FIGURE 6-5. Effect of a 20% change in component costs on
average total cost per pullet survivor at 5% production.
FIGURE 6-6. Average total cost of a dozen hatching eggs for
the STD and -24% feeding programs, with age.


Page
152
Missing
From
Original


130
rearing costs, while lowering producer payments. BMRT was
costly on two accounts: first, by raising the ATC/B; and
secondly, by lowering average breeder hen production.
Average cost budgets on a ATC/E basis are presented in
Table 6-6 for various feeding programs. Relationships among
cost components are similar to those discussed on a survivor
basis. The slightly higher level of cumulative hatching
eggs for the -24% program was able to offset previous
differences in feeding programs due to salvage adjustments.
Essentially, the ATC/E for the STD and -24% programs were
the same. This implies that by 67 wk of age the additional
PL$ charges resulting from the -24% program can be offset
by BFD savings and increased production despite the salvage
advantage for the STD program.
It is important to note that a major difference between
these two feeding programs at this age was the level of egg
production. Experimental data resulted in a significantly
higher rate of production for the -24% program (63.4%) than
STD (51.9%) at 64 wk of age (Chapter IV, Table 4-4).
Prediction equations based on these experimental data
projected economically sound (decreasing ATC) levels of
production for the -24% program through 78 wk of age.
The changing relationship between breeder hen costs and
production (ATC/E) with age is illustrated in Figure 6-6.
This plot demonstrates that ATC/E for the STD program
reached a minimum ca. $1.17 /DZHE at ca. 72 wk of age*


The effect of quantitative feed restriction on breeder
hen reproductive performance was determined. Proportional
decreases in feed allocation below standard practices
resulted in corresponding decreases in body weight, double-
yolked eggs and number of days in production to 64 weeks.
Egg weight, fertility, hatchability, and female mortality to
64 wk of age were not significantly affected by feed
treatment. A delay in sexual maturity caused a significant
decrease in average hen-day production to 64 wk, but not in
total settable eggs per hen-housed.
The effects of feed restriction on attributes
associated with sexual maturity (comb, bursa, fat pad,
plasma lipid, ovary, oviduct, and shank), were
characterized. The main effect was a delay in the
development of these attributes without significantly
altering their ultimate physiological values, with the
exception of shank length which was permanently reduced by
severe feed restriction.
The economic effect of severe feed restriction on
pullet rearing and breeder hen cost structures was analyzed.
Average pullet rearing cost was increased by ca. 3% when
feed restriction delayed maturity by 3 weeks. The resulting
increased pullet depreciation cost was not offset in the
laying period until ca. 67 wk of age. Projected average
total costs beyond 67 wk were lower for severe restriction
than standard feeding practices, especially if pullet
housing density is adjusted to an equivalent bio-mass.
xiii


128
sensitive to PMRT at these ages or base levels used in this
analysis, even though it had a negative economic effect on
both CHK and PFD costs. Increased pullet density had an
important positive impact on ATC/P. The relative importance
being almost equal to CHK costs at the ages tested and
greater than PFD costs at 20 and 25 wk of age. ATC/P became
more sensitive to changes in pullet housing density with
age.
Sensitivity analysis performed on cost data from the
-24% program is illustrated in Figure 6-4 and revealed that
ATC/P was more sensitive to changes in CHK, costs at 20 and
25 wk than PFD costs. PFD, CHK and PPAY had nearly the same
relative impact on ATC/P at 30 wk of age. ATC/P was
relatively non-sensitive to PMRT at each age tested. At
base prices, the ATC/P for the -24% program was ca. .252,
.398 and .525 dollars lower than the STD program at the
common age of 20, 25, and 30 wk, respectively.
Figure 6-5 illustrates the change in magnitude of
P/ATC, at the base price situation, to a 20% increase in
PMRT, PPAY, PFD and CHK costs at 5% production for each
feeding program. Also plotted is the expected decrease in
P/ATC resulting from a 20% increase in pullet housing
density (DNSTY). This plot indicates that at 28 wk of age
(5% production for the -24% program) the ATC/P of $5,720 was
lower than the ATC/P of $5,834 recorded at 25 wk of age or
when the STD program reached 5% production. Savings from a


36
ME/bird/d and 19 g of protein were sufficient to maintain
normal reproductive performance of individually caged
broiler breeder females through peak egg production. At 36
wk of age they noted an unexplainable accelerated decline in
egg production along with a drop or no gain in body weight
between 32 and 36 wk of age. This suggests that inadequate
feed allocations were made at this stage and perhaps the
ideal level of energy intake should be higher than the
reported 385 Keal ME/bird/d.
Research conducted by Leeson and Summers (1982)
demonstrated that excessive energy intake resulted in early
maturity and reduced numbers of settable eggs. Early
maturing birds gained more weight post peak than the control
group even though the feed allowance was identical. This
implies that over-fed birds divert feed energy to body mass
rather than egg production. Peak egg production was 10%
lower than standard and egg size was significantly smaller.
Because obese birds have a higher maintenance requirement
than lighter birds when they mature, initial egg size is
smaller and often not suitable for incubation.
Protein
Waldroup et al. (1976) found that the protein
requirement over the entire production period of broiler
breeders raised on litter and fed a corn-soy diet without
supplemental amino acids was approximately 20 to 22 g/d.
Wilson and Harms (1984) revised their original


o= +8% 0= STD <§>= -8 FIGURE 5-8. Effect of feed treatment on ovary weight (g)
with respect to age (wk) and body weight (g)


Table 4-7. Effect of feed treatment on mean ( SEM) hatchability of all eggs set (Hatch)
and fertility (Fert) at various ages.
__ Feeding program
Age
, (wJc)
+8
%
STD
-8
%
-16%
24
%
Pooled
32
Hatch
82.0
+ 2.9a
84.0
3.1a
80.8
4-2.1
82.5
+ 3.3a
75.8

2.3a
81.0
*4" 1 2
Fert.
91.3
3.7a
94.8
.6a
92.0
4-2.7
90.5
3.3
90.5

3.2a
91.8
1.2
36
Hatch
87.0
+ 2.1a
92.0
+ 1.5a
86.8
+ 5.7a
84.0
2.9
91.0

.6
88.2
+ 1.4
Fert.
95.8
1.3
95.3
1.9a
94.5
2.9a
91.3
2.9
96.5
+
.7
94.7
.9
40
Hatch
86.0
+ 3.8a
88.3
1.8a
87.5
4 2.7
85.0
+ 4.2
84.5
+
3.0a
86.3
+ 1.3
Fert.
92.0
2.1a
95.3
1.3a
95.0
2. Ia
90.0
3.9
93.0

1.3a
93.1
1.0
46
Hatch
85.3
+ 4.0a
79.0
+ 2.7a
80.3
1.3a
83.8
+ 3.1
81.5
+
2.6a
82.0
+ 1.3
Fert.
90.0
3.2a
81.3
3.2
85.5
2.6a
89.5
2.4
85.0

3.5a
86.3
1.4
52
Hatch
85.3
+ 3.6a
83.0
+ 2.6a
82.8
+ 2.9a
82.5
+ 2.1
82.3

2.1a
83.2
+ 1.1
Fert.
91.3
1.7
90.0
3.6a
91.3
1.6a
89.5
3.8
86.8

1.8
89.8
1.1
56
Hatch
79.3
+ 3.4
80.0
+ 3.5a
74.0
4 2.5
81.8
+ 2.2
77.0
+
2.5a
78.4
+ 1.3
Fert.
91.8
1.3
93.5
2.9*
87.8
2.3
92.3
2.0
92.0
i
1.7
91.5
-9
62
Hatch
83.5
+ 4.0a
84.0
+ 3.0a
80.8
+ 2.2a
85.5
+ 3.3
82.8

2.0a
83.3
+ 1.2
Fert.
92.5
1.9
90.8
2.7a
91.8
1-8
90.0
+ 5.4
90.0
4
2.6a
91.0
1.3
64
Hatch
75.3
+ 1.4a
75.0
4- 4.0a
78.5
+ 2.5a
78.3
4.0
72.0
+
1.7a
75.8
+ 1.3
Fert.
89.8
1.8
93.0
4.4a
89.8
3.4
91.0
4.3
88.5

3.6a
90.4
1.5
Pooled
Hatch
82.9
1.2
83.2
+ 1.3a
81.4
+ 1.2
82.9
1.1
81.3
1*2
82.4
+ .5
Fert.
91.8
-8a
91.7
1.2a
90.9
.9a
90.5
1.2
90.3
1.0
91.0
.5
a,b Row means followed by different superscrips differ significantly (P<.05).
03
Cs


139
TABLE 6-5. Effect of feeding program on breeder hen average
cost budget through 40 weeks of production, calculated at
base prices and expressed as dollars per survivor
Feeding Program
+8%
STD
-8%
-16%
-24%
Performance factors
Age, wk
64
65
66
67
68
Livability1, %
.93
.93
.93
.93
.93
Feed, kg/Surv.
45.40
44 >65
44.33
43.72
43.28
Hatching eggs,
doz/surv.
13.000
13.295
13.640
13.130
13.480
Averacre Fixed Costs
/ Breeder hen survivor
(AFC/B)
Pullet rearing
cost, (PUL$), $
5.745
5.834
5.901
5.958
6.005
Averacre Variable Costs / Breeder hen
survivor (AVC/B)
Feed, $
5.674
5.582
5.541
5.464
5.410
Prod, pay, $
3.900
3.988
4.092
3.939
4.044
Service &
supervision, $
.300
.300
.300
.300
.300
Averacre Total cost /
Breeder
hen survivor (ATC/B)
$
15.619
15.704
15.834
15.661
15.760
Salvacre adiustment /Breeder hen survivor
Egg salv., $
Hen salv., $
.131
1.075
.131
1.050
.131
1.021
.131
.981
. 131
.978
Adjusted
ATC/B, $
14.413
14.523
14.682
14.549
14.651
breeder mortality begins at 5% production and not at a
common age.


BIOGRAPHICAL SKETCH
The author, Thomas Richard Fattori, was born on
December 24, 1950, in Teaneck, New Jersey. He graduated
from Don Bosco Preparatory High School in 1969. Thomas
studied animal biology at Washington State University until
he received a Bachelor of Science in Animal Science degree
in 1973. He then spent 10 years working in the area of
international agricultural development in Francophone Africa
and Europe. His cross-cultural experiences included
logistic and market surveys, feasibility analysis and
project planning. He is fluent in French and has traveled
widely throughout the world.
Thomas received a Master of Science in Poultry Science
from the University of Florida in 1987. His major field was
poultry management with a minor in farming systems.
Thomas is presently completing a Ph.D. degree in animal
science with a major in poultry management and a double
minor in farming systems and food and resource economics.
He is working under the direction of Dr. H. R. Wilson
(physiologist) and Dr. P. E. Hildebrand (production
economist). His duties include being a farming systems
171